Hi:
Having been many times over the years, the biggest suggestion I have is not to run from one end of the parks to the other. In other words, when you enter the Magic Kingdom, get your map. Then go up Main Street (you can do the shops on the way out or another day), then either go to the right into Tomorrowland or the left to Adventureland. If you start with Tomorrowland, check off each attraction as you do them. Don't try to go from Space Mountain (Tomorrowland) and then jump over to Splash Mountain (Frontierland) because you'll waste all your time running back and forth. The lines move quickly so just finish one Land before you move onto the next. Then if there's time, you can go back to your favorites. Also, since it's your first trip, you may want to do lunch at one of the many quick counters and maybe do dinner off site or one of the sit down restaurants. I suggest this for all of the parks. Remember, if you miss anything, it's a reason to go back. Also, take breaks, buy an ice cream or popcorn and sit on a bench and regroup and look around at the beauty of the place. You want to enjoy the trip, so take your time and you should be able to do all the parks. Like everyone else has said and I agree, give yourself some down time. Have a wonderful trip. Hope to hear from you when you return.