On weekdays, it is much less crowded in the morning than in the afternoons. So do your best to get there early and do the rides you care about most first. For example, Autopia has about a 10 minute wait in the a.m. and a 30-40 minute wait by early afternoon.
If the line to ride the tram from the parking lot to the park is really long, it can be faster to walk through Downtown Disney instead of waiting.
I always bring in snacks and a full lunch for my toddler, plus water, and they've never stopped me even though you're technically not supposed to bring in outside food.
If you can buy your tickets in advance, it will save the time of waiting in that line, too.
The submarines always have a REALLY long line and most people I know say the ride isn't really worth it. So that's one to skip unless your kids are completely obsessed with Nemo.
The other main thing I learned is just to have fun and not stress about lines or how many rides you do. Yes, it is very expensive to go, but if the kids are getting tired/melting down/need a break, it's a lot more fun for everyone to just take the necessary break than to keep on pushing.
Have fun!
K.
http://www.discoverytoyslink.com/karenchao