Always, always, always try to contact your POI before applying. The worst that can happen is that your e-mail falls into a black hole. Before contacting your POI, make sure you have a pretty good idea of what you want to do -- and what your POI does. But speaking as a POI, I'd rather have an unprepared scholar contact me and walk them through putting an application together, than getting an application from someone who clearly needed more mentoring and wouldn't be able to get into programs with the portfolio they submitted.
Furthermore, with some programs receiving hundreds of applications, the first evaluation of applications is often made by faculty outside of your particular regional/topical specialty. If a POI knows to lookout for an application, they can often rescue someone who was passed over in the first round. But if they don't know about you, your application can get lost. This has happened at all the schools I've been at, so it's not particular to my current position.