I agree with EsmeraldaX, you're best bet of getting done what you want is to be at the FRONT of the EMH line or on a non EMH day the entry line. Especially with security, it takes a longer for people to go in and being one of the first on the busiest ride is such a plus, I think. I'm not sure what it's like now and I'm really nervous about our upcoming trip. I usually try to get there on the average of 45 minutes before opening.
Hit the headliners first, at MK, EMH really helps I think, because the Splash Mountain side of the park is not open until 9:00, so you can get several of the headliner Fantasyland/Tomorrowland rides done from 8-9 (Space, Buzz, Pooh, Peter Pan) and then be in line for Frontierland to open to do Splash, Big Thunder, HM and Pirates.
It all depends on what rides you want to do. The worst (I think) is when you have someone that wants to do Dumbo and others that want to do coasters. The only answer to that one is FP's for the super headliners.