You can have 4 characters per account, since you can only unlock the skills of your primary and secondary profession it would be a good idea to make a couple RP characters that don't share the same classes. Your RP characters can become PvP characters eventually, so keep that in mind.
For instance, I have a Warrior/Monk and a Mesmer/Elementalist that are RP characters. The Warrior/Monk is PvP ready and the Mesmer/Elementalist will be soon.
So with those builds I have unlocked a substantial amount of skills, weapon upgrades and runes (armor upgrades) for 4 of the 6 professions. At any time I can delete and remake my PvP only character to take advantage of any combination of those 4 professions. (ie Warrior/Elementalist or Elementalst/Monk for instance)
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