Writing this part of the guide will be a daunting process so for now, I would recommend joining a WvW guild that can show you the ropes. Next best option is to see whether there are any commanders on the map with open squads. They’ll often have a discord/teamspeak that you’ll want to join to at least listen to what’s going on. If you’re looking to pick a server who is going to be active during your preferred time zone, use WvWstats as a reference. You can also watch this new video by Mukluk as an introduction.
For a basic guide on what WvW is, check out this one by TheValiant in conjunction with metabattle’s. Metabattle also offers some roaming builds (solo/small group play) and zerg builds (meant to be used in large groups), but like anything else, you’ll find what works best for you through experience and based on your individual playstyle. WvWintel is useful for keeping track of how your world is doing without being in-game.
One of the earliest goals you’ll want to aim for in WvW (Expansion only), is to obtain the Warclaw mount first, since PvE mounts are NOT allowed within WvW. Use this guide created by Dulfy and you’ll have it in no time.