Most important is to have nice weather day and to get the fastpass tickets. The number one thing to know about Fast Pass is to get your first ticket as soon as you walk in the park. This is the same for the Movie Studios or any of the other disney theme parks. Focus on the Fast Pass through out the day.
I would tell most people go ahead and do Space Mountain the first thing you can when you get there using fastpass. How can anybody pass up a Roller Coaster in the dark and one that is so beloved and highly rated. If you want to check it out ahead of time, go on the People Mover. The People Mover is part of Tomorrowland and it's a ride that takes you through some of the other rides. When it travels through Space Mountain you can hear all the people screaming. I thought the People Mover was fantastic as it really does expose you to the inner workings of some really neat things including the Buzz Lightyear Ride. There is just something about Space Mountain, because you don't get to see the people riding around on the roller coaster like to do on Big Thunder Mountain. You can do all the good rides in the Magic Kingdom in one day. Focus on the fast rides forget about peter pan's flight!