Really none of them are suited for a fresh lv20 newbie, not with all the high-level ultra awesomes running around.

But I guess the safest, if you know what you're doing, would be the Trader.
See, Hunters and Thieves are purely PvP jobs- to get experience for those, you will
have to kill other people at some point or another. But a Trader, doing a 1-star trade, avoiding 1-star popping thieves, is a great way to earn decent amounts of money.
Read my Guide and others here to learn about the jobs and how to play them.
Btw, what is your character's name on Planeshift? Would I remember you? :3