Things I wish I known when I started PvP'ing:
1. PvP deaths aren't always a bad thing. It allows you to respawn at any keep your faction holds (unless under attack), it also allows you to respawn at any forward camp. So if you want to reach a keep quickly when transit line is cut of, than go suicide at the closest enemy resource. Dying from opposing factions NPC's counts as PvP deaths, so free transport yay.
2. People saying stuff like "attacking Ash type 123" are using an addon with auto invites. By typing 123 in zone chat you get automatically invited to the group. Anyone can join.
3. Always jam down block in cluster/zerg fights. Keep the key pressed down constantly, while casting skills. As soon as you're finger starts slipping you will die or get knocked down or in the air. Same goes for crouch. Do it as soon as you dismount in enemy territory.
4. You can actually use cc-break against Negate Magic. Popular doom skill used by sorcerers, but more frequently spammed by OP enemy NPC's.
5. If someone attacks you while mounted, than dismount asap and block. You will probably die if you try to ride away. The dismount animation, when the horse falls over you takes a few seconds to shake of, it gives the player plenty of time to kill you.
Also get a Restoration staff, even if you're not going to fight with it. Spamming HoT's it's the best way to build up Ultimate before facing the enemy.