Well, luckily you've decided to start in PvP when a new season is about to start (perfect timing) because this means that every else will be earning the new seasons gear at the same time you are. Right now, you can earn Tyrannical gear (496) with honor from the PvP vendors, which is the same gear everyone got last season - so you'll be in the exact same gear as everyone else going into the new season if you're gear up now.
Gear is fairly expensive per piece (1.5-2.2k honor per piece), but if you do the
Tol'barad weekly, kill these NPCs at the Dominion Offensive (
Dalan,
Disha and
Mavis) and BG inbetween their 45-60 minute respawn times, it shouldn't take
too long to be fully geared. And, as Lazy Gecko said, if you don't feel comfortable in BGs in your current gear you can either get crafted PvP gear or even get ilevel 496 gear from timeless isles, PvE gear is still pretty good - just isn't the best.
As for learning how to PvP, it's worth checking out PvE guides to get a feel for the rotation and to know how to do the best damage possible - even though some of it wont apply to PvP, it's definitely worth knowing what the ideal damage rotation is. Secondly, check out
this guide (someone might have a better one, this is the first I came across and it seems okay). One thing to note is that guide probably isn't updated for 5.4, where a lot of changes happened for Warriors. If anything doesn't add up, play around with it yourself and see what feels/seems better.
During the new season, see if you can find other people to cap with you each week. There will probably be channels etc for finding Arena partners now you can group and queue through battletag, I know a site which is trying to push for an Arena chat where you can find partners. If you enjoy capping with some of the people, add them to friends and see if they want to push for rating some time. Eventually you might find a third and you can try out 3s.
Good luck!