I'm assuming you're healer (durr hurr you are, I reread your post)if according to your profile info there so let me say that you absolutely have to have swiftcast and surecast on your bar if you don't already.

The main thing you'll get for 30/40 pvp outside of wolf marks for level 50 gear is pvp xp for skills. You will probably want to invest in purify first then attunement or sacred prism but really that's up to you and how you want to spend your points as resets cost marks as well. Most people who gear up for low level pvp will craft the a level 40 HQ armor set and load it up with materia since that apparently gives the best stat bonuses compared to what level sync does to you normally.

Healer is probably the hardest role to play so don't get discouraged if you have a streak of bad games. Everyone has their first time so we've all been there.