New to WvW

Who ever gave you the impression that people who play WvW don't like people who play PvE should get slapped silly. Everyone is welcome and every single person we can add to the field in WvW is greatly appreciated. These days even more so than a week or 2 ago.
Our WvW numbers have been dismal this week and I for one would welcome any PvE player even if for just an hour or two.

Be careful though, WvW is addictive

Being good at WvW depends on the role you want to play.
If you want to roam about and capture camps and engaging the odd 1v1 or 1v2 here and there then just find a build that suits you. There are a lot of players that run around all maps in small groups (2s, 3s and 4s). Even taking the odd tower here and there.

If you want to get involved in taking towers fast and attacking keeps or Stone Mist Castle then you probably want to roll around with a zerg. The zerg is normally headed by a commander (the blue dorito on yer map). The commander is in Team Speak (will 90% of them). So before worrying about gear or stats, download Team Speak so that you can get real time info on what the commander plans and instructions are. Map chat is too lengthy and most people don't react to map chat until it's already too late...
After this you want to boost you Power, Toughness and Vitality (or PVT for short). It's crucial that you are a tough bastich that does not die instantly over and over because for the zerg to succeed in it's goal, as few people as possible should be rezzd along the way.

Crit chance is not really required because with high power and might buffs from fire fields (read up on combo fields and blast finishers) you will probably dish out as much damage with normal attacks than with critical attacks.

Other than that you should enjoy and don't mind dying... because you're going to die... a lot... Really, really, really good WvW players are few and far between so don't worry about not pulling your weight. Your presence is always welcome!

Run bunker builds.