Keep in mind that Universal Studios Hollywood as a whole is half a day. So if you arrive fairly early in the morning, you might get into the attractions earlier without going through the long lines the people might pile up when most of them would arrive in the afternoon. Despicable Me ride is notorious for long lines so I suggest you go there the moment it opens. Then start with the big ones such as Harry Potter, the Studio Tour, and the Lower Lot attractions where it has Jurassic Park, Transformers, and the Mummy ride. Go to Transformers first if you're willing to go on a simulator ride (and because the lines are longer for it), then Jurassic Park (the second slowest), and the Mummy (lines move very fast). You have to check the Universal Studios Hollywood time opening app if you download it. If you don't want to wait for these attractions and just want to get on as fast as you can, there's a single rider that if you and your family are willing to separate and wait for each other.
You could do a bunch of stuff in the City Walk after you're done or you want to go to the same attractions all over and over again. But if you arrive early, it's a half a day park, not even the Studio Tour can make up for it. Morning is the best thing, otherwise, by the afternoon or soon, it's gonna get filled up. Get in line as fast as possible or good luck waiting in line that might take almost half the time as finishing a two-hour movie.