Want to PvP but don't know where to start.

[mrpopo900]

Where can i get gear? Should i just do BGs until i have enough honor to buy some epics? At what point should i start doing arenas? How to even do them?

[Frostembrace]

My advice would be to get some basic PVP gear from AH first if you can, or at least some epics from RDF. Don't go in BGs all green, you will suck a big one and there is a good chance your team will make unpleasant remarks ;)
Do BG's to get honor, for which you'll be able to buy some wrathful/relentless/furious (PVP) items and by all means play Arena even if butt naked. To my knowledge you don't have to win a single one, as long as you play at least 10 rounds a week (in the same team). Arena reset is on Monday, that's when you'll get your arena points.
Once you'll be better geared and your arena rating will rise you'll be able to get better gear, by that time you'll figure it out by yourself. To play Arena you'll need to find a partner and create a team (Dalaran's underbelly). Good luck!

[dike]

^^ pretty much this. craft/buy pvp set (ilvl 187) and offset. it will bring u to 700-750 resil. after that just start bg farm. at least no one will blame u for joining in green quest gear

[Avagg]

You can go and try in Blackrock realm you recive full pvp gear(non hc pve),jems,encgants for free at any class.And roll bgs duels and if you desire arena as well.That is one of options if you want only pvp. and nothing ealse.

[MrRufus2nd]

start by learning how the classes counter each other and more relevent info to you such as if your hunt you should know your counters and cc's so you can work to be better at slaying people. try it out to see how much you enjoy it. i would start in battlegrounds where it is much more forgiving and to watch people duel outside your factions city as to see how more experienced people do things. if you want step by step i will offer it to you.

1. buy decent armor to replace potato armor
2. learn your class and other classes, there are videos and forums dedicated to teaching most aspects of it
3. join bg and practice skills and to get more honor to get gear
4. once you feel abit more settled into your pvp skills then i would suggest doing more duels and even joining arena to get better at taking out people
5. stroke your e-peen and afk outside faction city claiming to be master

im not too into pvp so i can be wrong af but i offer this as a potential guide path. hope this helps.