Normally, you RP with people you don't know to be friendly with tells. Not everyone is going to PK you, but if you just walk up to someone without saying a word, they might see it as an incoming attack and strike you or quaff a potion. Often, if they are friendly, they will let you know they are there to let you know that they don't have ill intentions. If someone PK's you, do following:

1. Get your stuff from your corpse.
2. RP with them via tells afterwards.

If you want to walk up to people and RP with them face to face, the Inn of Eternal Star is the best place for this. Lowbies won't generally attack people there.

In CF, playerkilling and roleplaying are deeply intertwined together. Everything a character does is supposed to be part of his roleplay. However, you should understand that people attacking you without warning is perfectly viable roleplay, not just lolPK, if their characters have a reason to do so and it is not against their role. It is the healthiest attitude to take and you're having much more fun if you consider their acts as part of their roleplay instead of regarding someone jumping you as lolPK. You don't know their role and they don't know yours. Talk with them via tells if you want to know why.

For an orc, it is perfectly valid RP to froth in the mouth and bash down an innocent bystander without warning. And run for the hills when your attack goes badly.