Maureen invited me to chime in here and I'm glad to give my off-the-cuff offerings!
1. First things first: Take some time to pray. Pray really hard that God will enlighten you and help you to discern what it is He wants your children to learn this year. Be still and listen. Look at the circumstances of your life. He knows them all and therein is part of His plan. Don't whine about the obstacles; dont' wish them away. Instead see them as opportunities to embrace His will.
2. Have a plan: Think this through. Really consider the best way to answer the charge the Lord has given you. Research materials; ask questions; watch what other people do. Then, take it again to prayer and come up with your very own plan. God knows you intimately and these are the children He gave especially to you. He trusts you to raise them for His glory.
3. Order your environment: Clear out the physical clutter and you will clear out the mental clutter. Everyone will think better if there is a place for everything and everything is in its place.
4. Get the routine down: Before the official start of "school," give as much thought to household routines (your character training curriculum) as you do to academic goals. Work dliligently on training those habits in the waning days of summer.
5. Refuse to over-commit: Do not overschedule. STAY HOME. As great as all those co-op activities look, take care to guard the rhythm of your days and to protect your energy level. Just say "no." Home education is about family--over-commitment will wreak havoc with a peaceful family culture. It seems the larger your family is, the more protective you must be of your time and your energy. Sacrifice the good (and there is so much good in the world of outside classes, co-ops, and activities) for the better.
6. Remember the airplane: On any given flight, the plane is off course most of the time. But with corrections and tweaking, it almost always arrives at its destination. So it is with home education. Don't despair if you are re-writing your meticulous plans by October 1st and chucking them altogether for Plan B by November 1st. Just keep praying and keep listening. You'll reach the destination.
7. Schedule confession and adoration: Make it a weekly family outing. You all need the grace.