Lease is dead on - get the parents on your side right away and keep them there. If you communicate well with them and treat their kids with respect all kinds of errors on your part will be forgiven. You will also be amazed at how much kids actually do to please their parents, so if their parents have your back you're going to get better efforts and more cooperation from the kids. It's like oiling the machine - everything works better.
Do everything you can to get every relay split from the 4x400 and 4x800 and make sure you record every time, distance, and height for every kid at every meet. Utilize a team manager or injured kids you trust to help with this task. Consider taking a couple JV kids you can count on to the invitationals to help with this as well and in return invest some time in them at the meet.
While the technical end of the sport is important, being organized enough to take care of the people is more so. A couple things I took away from a recent conference:
1) recognize the presence of every kid at every practice
2) recognize each kid's contribution on a regular basis - let them know that they matter.
3) remember that everyone wants to have fun even when they're working really hard
4) make sure they feel like they are an important part of something larger than themselves.
This all means that you need to have your #$*(&^ together before you get to practice each day. If you're stressed out it's going to be hard to take care of these very important but non-urgent matters.
... there are so many others things to say, but I'm sure you'll have lots of good ideas by the end of this thread.