Book for the entire family at once. Make sure everything is set up today so you can start immediately at midnight without any surprises (ie, are all family members in; does everyone have a ticket, etc).
I've only skipped some of this, so I may be repeating what others have said:
1) If you CAN Fastpass Elsa and Anna, do it. Seriously. You'll still have to wait a little bit, but the lines are insane otherwise.
2) If you CAN'T Fastpass Elsa and Anna, you'll want to hit it first or not at all, but remember that probably about 1-in-3 people at Rope Drop is also headed there. Also, Elsa and Anna don't arrive until 8:30 or so, so even if you're first in line, you'll be losing valuable time.
3) Depending on the make-up of your party, consider having one adult wait in line while the other(s?) take the kids to rids that can accommodate 3, like Peter Pan and Small World. That way, you can knock out a few rides rather than losing much of the valuable first hour.
I don't know if things have changed, but when we were there in November, only one person needed to be on line to "hold the spot," but obviously, you couldn't get in until everyone was there. I had my whole family there, but the guy in front us us was holding a spot for his family -- which hadn't left the hotel yet! When we got to the "inner hall" with the princess paintings, he just pulled over to the side and let everyone past.
If anyone has more recent intel that this won't work anymore, please sound off. I don't want to steer the OP in the wrong direction.
Beyond E&A, you'll want to blitz as much of Fantasy Land as possible before the park crowds up. In particular, Seven Dwarves, Peter Pan, Winnie the Pooh, and Ariel's Grotto (for signature) fill up quickly. The lines will only get longer throughout the day.
One thing to consider: Both Winnie the Pooh and Dumbo have fun stuff for the kids to do while waiting, so even if they get a little longer, it's not terrible (for the kids at least!). My daughter was upset when we Fastpassed WtP last year!
Good luck and have fun! (That last part is the most important thing to remember when planning!)