I'm a white mage too and I love the PvP in this game (except for long que times). Some tips I can give a new pvp white mage are:
1. Be ready to run the whole match. PvP is a lot different then PvE, no one will be able to protect you so you have to kite pretty much the whole time. If your opponents go after someone else, like the black mage, I recommend keeping your distance but try to help him/her at the same time.
2. When it comes to PvP actions, the two I recommend learning first are Attunement and Equanimity. I'm not sure which you should get first, I personally love Equanimity but I got yelled at for not having Attunement so you decide. Also eventually Purify is a must.