Aside from plans in the guidebooks, what is the best strategy for Universal Orlando, both parks?

At Islands of Adventure, the best strategy right now is to get there when it opens and head back to the new Harry Potter section first thing. That's the busiest area of the park since it just opened and will certainly remain that way for a while. Then after that, the coaster Hulk is probably your next longest line, so you may want to circle back and hit that. Beyond that, that park is quite small and can be easily done in a day, even in the busy summer. So you can just kind of go where you want.

Universal Studios is bigger. If you want to see any shows, and there are some pretty good ones, pick up a guide and more or less plan your day around the showtimes. The longest lines at the Studios will be the coasters, Mummy and Rip Ride Rockit. So I would head to those first and then go from there. This park has more to do, so it might take you 2 days, particularly if you want to see some of the shows. If you just move quickly from ride to ride, you can do it in 1 day.