I agree with everything Mostly Harmless posted above, for the most part. He's got some great points. Keep in mind you'll still get PK'd by people - Imperials will kill you for not being one of them, for instance...but his suggestions minimize your enemies as much as possible.

One other piece of advice - only play one char at a time. Even if you get a great idea for this really cool race/class combo...write it down or something and save it for after your current char. Make a rule for yourself that unless you con-die, age-die, or simply *can't stand* to play your current char, you never roll up anything new. It sounds like it won't be fun, but trust me, it makes for a great time.