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.
That goes for not snaking bodyboarders as well. It is a different scene down in PR. You might pay dearly if you do... they call them reefs for a reason!