best quests for newbies?

[Little Sara]

Thief can do 1-40 in a few hours with no real equips and no money (meaning a Main Gauche[3] until you can afford a NPC Stiletto[2]). Then 40-55 (Or Assassin job change) in 3-4 hours (with the Stiletto[2], with no cards).

As Assassin, it really depends on what you do and how you level (dd, crit, grimtooth?). I suggest getting Pantie + Undershirt asap, it's very cheap and helps a lot.