Definately do not snake any of the locals...esp at places like Jobos...i have seen people get chased out of the water for calling off a local dropping in on someone. Other than that...watch your belongings and remember where you get in the water...get out at the same spot or you risk being an urchin magnet.
I too may be going to pr in mid-late march. I've never been and will be going with my girlfriend who does not surf. So my time in the water may be limited. I was looking for places at aguadilla Where are you staying at?