Go early and use Fastpass whenever possible. But plan your Fastpasses accordingly, since you can only have one Fastpass issued to you for a certain amount of time before another will be issued to you.
We found that we were able to accomplish quite a bit in the first few hours after a park opened up. Even if we weren't there right at opening, we still got a lot done by 1 pm.
We found that a park had less people the morning after its evening EMH. We went to MGM on a Monday morning, after Star Wars weekend and EMH on Sunday night, and we walked on practically everything until about 2 pm. Playhouse Disney's first showing at 10 am was only half full and dh was able to walk on RoR. There was also NO lines to see Sorcerer Mickey and other characters, such as JoJo and Goliath. Meanwhile, parks are usually packed for evening EMH, but if you go in the afternoon of an evening EMH, it is usually not that packed, since most people may be resting to prepare for their late night.
HTH!
Linda