The lotro guild I am in make a player go through a 2-3 week period of recruitment period. Where as the recruit, contacts an officer to set up an instance run or what not with members of the said guild to run with. Then the members post flaws/skills that the member possesses, and why they would be a valuable asset to the team. (remember this guild is high end raid/pvp)
Recruits must have enough play time with guild members/officers, and play through atleast two successful raids before actually being accepted to the guild. Once they are part of the guild, they are allowed to roll on loot in raids. Instance runs are FFA.
As for PvP, if anyone truly loves PvP they should already know the basic ropes. (ie know player classes, and greatest disadvantages of those classes). Obviously, it takes much knowledge to truly be great, but knowing your class inside and out is the best skill you can obtain in any aspect of an MMO.