I would suggest looking for a class/race combo that does not look to be to complicated. Some class/race combos just have more easily usable tactics that would probably be easier to get the hang of at first. Other then that play something with some defined enemies, this will make it easier to find pk oppurtuinites (If you play a neutral neurtal sphere peace herald it might be hard to justify fighting alot ).

All classes are different though so learning to pk with a fire giant sword spec is not the same as learning to do it with a elf invoker. That said I would avoid mage classes at first and focus on more melee oriented classes, warriors, assassins, and rangers.

If I was forced to recomment something I would take a giant warrior sword spec or a svi warrior axe spec as they have some pretty easy tactics you should be able to figured out.