... If anyone has more to add here, feel free! 
Tip #1 - Pray with your dc that your homeschooling day will bring the Lord glory and be full of happy memories made together! Pray that the day will go smoothly and that the family can work together to enjoy learning. Thank the Lord for making it possible that you can homeschool your dc, and that they can be home together to learn.
Tip #2 - Plan a happy start to homeschooling! Be cheerful, give hugs, show the dc their things with excitement. Attitudes are catchy, so if you are excited, they will probably be more excited.
Let the dc know that you view being their teacher as a privilege, and that they are some of your favorite people to be around. Also let them know you are the teacher, and as such, are "in charge". 
Tip #3 - Give each child a copy of the routine or schedule, or if you are less scheduled than this, explain how you expect the day to go. Have them read through their schedules. Give them their guides and have them look over their day's plans. Show them where their art supplies will be kept, where their books will be kept, where to hand in their work (we like to have them hand in things open to the page to correct on a designated area on the kitchen counter), and where they will work for each box. Let them know what time they will be starting school each day and any other guidelines you expect them to follow.
Tip #4 - Describe the attitude you expect from yourself and your dc. For example, in our home, we often say work must be done right away, cheerfully, completely, and obediently.
If dc (or if we ourselves as teachers ) are not doing this, have in mind a consequence. For example, in our home, a timeout with nose to the corner standing near me for a set time (i.e. 1-5 minutes, depending on age of child, more for olders, less for youngers), works well. If I need an attitude change, a hot cup of coffee and a moment to collect myself as I drink it and pray for patience works well for me. Remind dc that school is their "job" right now, and that the Lord created us for work. Doing our work well brings the Lord glory, and that includes doing our school work well, to the best of our ability, with the best of attitudes. Be consistent in enforcing this attitude - work habits are lifelong lasting! Tip #5 - If you are doing multiple HOD guides, explain how you have planned for divvying out your teaching time - when you have planned to be teaching each of them, when you may be "floating" between them to teach several different things at the same time, and when you expect them to work independently and not interrupt you teaching another child. Here is a link describing the "floating" way of teaching several dc different things at the same time...
viewtopic.php?f=6&t=2093&p=35802
Tip #6 - If you have planned for older dc to each have a playtime with younger dc, show them where this will take place, what they should do, how you expect it to go, how long it will be (consider setting a timer for them), and that you want everything cleaned up with the little one helping as able. Remind the older child that this time is all about the little one - not them. So the playtime and activities should be chosen with the younger child in mind, and to entertain the younger child, with the older child's interests set aside during this time.
Tip #7 - If you have little ones (i.e. age 5 on down), know what they will be doing. Consider having a plan in mind for them that accounts for every 30 minutes or so of the school day. Little ones (especially toddlers) must be planned for in order for the homeschool day to flow smoothly. Consider doing LHTH with your little ones, even half- speed, as it gives purposeful mommy time with the littles and fills their little emotional love tank nicely, while only taking 15-30 minutes (depending on if you are doing it half-speed or full-speed). Here are some wonderful threads about things your little ones can do to make the day go more smoothly...
What to do with toddlers while schooling:
viewtopic.php?f=5&t=198&p=33557
viewtopic.php?f=6&t=4987&p=36744#p36744
viewtopic.php?f=6&t=9569&p=69865#p69865
Carrie’s post about what to do with Toddlers:
viewtopic.php?f=6&t=9569&st=0&sk=t&sd=a
Guilt about not spending enough time with toddlers – ideas for sharing our time between toddlers and olders:
viewtopic.php?f=6&t=6412&p=46859#p46859
A post I did about planning a rotation of independent activities for our 4 yo, that may be helpful...
viewtopic.php?f=6&t=10565&p=76777#p76777
Tip #8 - If your dc are using PHFHG on up, teach them how to use their HOD Guide as a Student Planner. Encourage this age of dc to read through the box of plans, gather the needed supplies themselves, etc., so they learn how to work independently on the things they are supposed to successfully.
Tell these dc that the corners of the boxes show how the box should be done, I = Independent, S = Semi-independent, T = Teacher-Directed. This thread explains why it is so important for dc to use the guides as their own once they are older and expected to work on some things completely independently...HOD Plans in the Upper Guides Act As Students’ Planner:
viewtopic.php?f=6&t=9650
Students should check off each box in the plans as they complete them. This helps them visually see if they have done all their work, and it helps us see as well. If you have multiple dc doing the same guide, have them initial the boxes, or if funds allow, get them their own guide.
Tip #9 - Plan 1-4 weeks to train dc to do each box of plans (more like 4 weeks if dc are new to HOD or are younger; if dc are older or are returning users of HOD, it will be more like 1-2 weeks). Work through each box alongside your dc, making sure they get into the habit of doing each one correctly. If the box is Teacher-Directed, plan to keep working alongside dc the whole year. If the box is Semi-independent, plan to help dc get started with that box and let them learn to finish it out independently. If the box is Independent, plan to help dc have the skills needed to do those boxes completely independently.
Tip #10 - Resist the temptation to add more work or more discussion questions to the plans, unless both you and your dc are fine with the school day going much longer than intended. For us, the only discussions we let go long occasionally are the Biblical ones, as this is time well spent since it has eternal impact. If dc are getting off topic, gently lead them back to the task at hand, and let them know they can finish out their off topic interests once school is done. This will ensure that dc don't get off topic or even extend a school topic during school and take so much time on their self-directed activities or extending their favorite school subject, that they don't have enough time, energy, and focus to finish out their appropriately balanced HOD day.
Tip #11 - If you are teaching multiple guides, consider slowing down to half-speed for the first week or two of school. This will give you time to focus on teaching each box's plans well without being rushed. Or, consider stagger starting your dc. Start first with one child and work alongside them for a week, and then start the next child.
Tip #12 - Check on your dc's work progress diligently. It is a rare child that can go to his room or be in a room alone and work diligently as efficiently as possible for much time successfully. Proximity of the teacher usually ensures good work habits form - though I find I must balance this with "hovering" too much.
Tip #13 - Set the timer for the amount of time suggested for each box. Help your child get used to monitoring his progress to that he can complete his work in a timely fashion by using the timer as a tool. If you have an especially artistic child, consider adding 10 minutes of time to the alloted time for extra creative touches - if they go longer than an extra 10 minutes, encourage them to set it aside and have them finish it at the end of the school day, so they can take as long as they want (but be sure to require them to finish what is in the guide).
We've found it is not necessary to use the timer all year for most of our dc. Usually after a month or so, they don't need the timer all the time, but rather for occasional brush-ups on managing time well if things begin to go long in a certain area. Tip #14 - Check your dc's work that has been handed in each day and help them make needed changes. This helps dc fix their errors right away, and it also helps keep us in tune with how they are doing. Work that is not checked one day will be waiting to be checked the next day, and two days' work is harder to correct than one day's work.
Tip #15 - As dc become older and more independent, add in some check-up times within the school day to meet with them and briefly check the work they have done independently. For example, this year in RevtoRev, at the start of my first teaching block of time, I start by checking what my ds has done before independently (which is science and Bible Quiet Time). For science, I use the answer key to check his EE workbook and help him revise his "theory" if need be. Last time, I told him he needed to have the chapter heading in his answer for his theory (i.e. action and reaction, centripetal force, etc.). This improved his theories so much! For Bible Quiet Time, I have him say his verses he's memorized for me, and check any work in his Hidden Treasures... book. If it's an oral narration day, he does that next for his Inventor Study, as he just read that. Then, we go into my teaching time by doing dictation, R & S English, Biblical Worldview/Music Appreciation together. After this he does more independent work, and then at the start of my next teaching block of time, we go through the independent work together first, checking it together. Then, we do our teaching time together. This helps me stay in tune to what he is doing and correct his work in segments.
All of this takes minimal time, but helps ensure he is doing all he is supposed to be doing correctly. Tip #16 - Find ways to encourage dc. Sincere praise, stickers, meaningful comments, hanging work on the fridge or on the wall, sharing work with Dad and praising dc in front of them as you do, hugs, little treats or healthy snacks together, working alongside dc when they find something difficult or are frustrated, etc., all go a long way to keep dc feeling positive about school and enjoying their time with you as their teacher.
Tip #17 - Avoid interruptions that make the day go unnecessarily long. This may mean not answering your phone and not getting on your computer during teaching time. For your dc, this may mean not checking their email, or not working right near a sibling that distracts them.
Tip #18 - If you are doing multiple guides, avoid having everyone do everything in everyone's guide. If each child is placed correctly, his guide is enough work and enough time for doing school. Doing everyone's school results in long days, and in the end, most dc are not able to fully apply themselves to their own guide then. Having 5 minute together times works well instead...
viewtopic.php?f=6&t=10875&p=79128#p79128
Tip #19 - Edit dc's work using HOD's suggestions. In general, have dc read their written work out loud to themselves before handing it in to you - many errors are caught this way on their own. After work has been handed, you can jot in the margin whatever is incorrect (i.e. write the way the word that is misspelled should be spelled, write a comma if it is missing, etc.) Dc then should use the notes in the margin to fix each thing in each line, and last you help them fix any mistakes they still didn't fix from the margins. There are also editing tips to work through in the Appendix of each of the upper guides. Dc should be trained to work through these one at a time. They have helped each of my older dc become careful, good writers in their daily work.
Tip #20 - Remind dc to work quietly so as not to disturb others working near them. Whistling, tapping, running through rooms, banging things, shouting out, interrupting - all of these habits distract others from doing their best work and are not polite manners. Our dc will be working alongside others some day, it's best they learn how to be a conscientious worker right away.
There are probably more, but those are the ones that come to mind now.
In Christ,
Julie
