well, at lvl 20 other than doing 1* trade runs you wont be effective at any job. You will be the lowest lvl at any job which means you will be owned at any job

. do 1* trade runs for the experience and try not to get 1* popped by thiefs. If a thief with a trade animal comes toward you turn around and DC from the game and log back on later and finish your trade run

. you wont be able to be a hunter or thief till you hit higher levels. you can try in your thirties but you still will get owned 99% of the time. Do your quests and 1*'s till you hit your low to mid 40's then start with the job aspect of the game.