Please, please, please take your time as everyone has suggested. What I bought at certification - I would never consider buying now. Not that what I bought was bad. It just turned out not to be up to the level that I now require. Do your research. The biggest problem with "trying out" via rental gear is that rental gear tends not to be the higher-end equipment. Find a good divebuddy - perhaps your instructor or someone else who has been diving for a period...then beg and plead them to try their preference out. It really is amazing how divers are really very willing to share their toys with others.