Universal can be pretty crowded in July...starts getting crowded around the 4th.
However, Universal is one of those places where there aren't too many ride / attractions where you have to wait in line. Many of the shows have schedules, and typically if you arrive 20 minutes prior to the show time (when they try to open the theaters anyway) you should be fine. You can bring food / drink into most / all of the theaters (I think the exception is T2), so you can plan to use some time to eat in the theaters, waiting for the show.
The tram tour is the heart of the park, taking you throughout the studios. Typically, the trams run until 6ish (it has been a while). I would save this for towards the end when the line shouldn't be too long (and the tour takes approx. 45 minutes.) Everyone typically goes here first, so take the time to go see the attractions with lines (Jurassic Park, Back to the Future, Backdraft, World of Cinemagic - just a movie special events deal - OK, but if you are running short on time, I personally would skip.)
Finally (sorry so long!) ASK cast members what they recommend! They know the place best, and can help you plan your day!
