Hi Bethcolumbus, Welcome to Cruise-Chat!
There is a lot of great information in the
Caribbean Port section of the forum about San Juan. Use the "Find" tab to do a search. One should always be careful in an unfamiliar area. Since your port call should be in the day time I wouldn't be too concerned. I have always found San Juan to be a very friendly place to visit.
Welcome aboard,
Dwayne