Tip for First-Timers/Only-Timers?

I know this is probably asked a lot, but I can't seem to find a more recent one.

My family and I are going to Universal Orlando for the first time ever this next week, for around 2-3 days. We're not looking to go to the water park or anything, just the main park, the Islands, and maybe a little City Walk.
My mom loves Harry Potter, so I know she'll want to see both portions of that in the park, but beyond that I think we'll just be enjoying what we come upon.

Any tips for the park, either for health or park movement? We haven't been to a huge park like this before and I thought it might be nice for some advice. Anything would be helpful, thanks.