Hunt mobs you can kill in 1 hit with/without using spirit shots.
However, dont hunt mobs with blue names because they wont give you enough xp.
I you cant find mobs that you cant kill with one hit, 2 hits is the max you want to go. But you might end up with mana problems and will have to sit down to regen mana.
The answer to your question is not exactly subtle.
If you are in top NG before 20, if you are in area of dev...for all intents and purposes if you can target it you can kill it (don't go too deep into soda, but otherwise..........)
Kill a lot of wolves and goblins. Then kill a lot of mushrooms and orcs. Then kill billions of spiders. Then kill soda orcs and skeletons.
Somewhere in there you will complete first class change (which will take you briefly to roa and gludio).
All kidding aside, the hunting area guide on your in-game map is a pretty nice guide.
Search for mobs white to you (generally)...if they die in 1 shot.
Use the newbie buffs.
If you're question is 'how to lvl dk wiz after 20' then u are definately gonna have to list gear u have before anyone can tell you much.
I like Langk area and outside of AC around 20. In AC from 21-26 or 27.
You can solo in first rooms of NOS by then too--no problem if u have good gear in mid-20's or are grouped.
My advice--melees should kill LOTS of mobs green to them to level. Dk wiz's should probably do the same---but you don't have to blink twice at mobs white to you. At about the time these mobs stop being easy with 1 shot you get twister and aura burn (twister becoming your primary attack for quite some time then).
It's an easy level to mid 30's--even mostly alone.
Remember, you don't just stand there and cast until the mob is dead. In L2 you "kite" the mob. Just in case you find yourself standing there, being attacked and you keep getting interrupted.
Of course if you can successfully one or two shot any mob without it reaching you then all the better.
if you want to know where to level from the point when you become a Dark Wizard (lvl 20):
Go outside of the West Gate of Gludio. Travel along the road towards RoA & Abandoned Camp.
1.) As you first start out you will see Spiders and Lizardmen to your right.
2.) As you travel the road you will come to a spot where there are mountains on both the left & right side of the road. That's where the Spiders & Lizardmen will stop being seen. At that spot take a left and travel along the bottom of the mountain until you see: Sometype of Eye mob, Some Spiders, and some Ratmen.
Level there until you are 23-25. The eyes and ratmen are not agro, the spiders are.
I went killing the spiders there (archinid predator or something i guess their name was) till I got to lvl 24. they give 799 exp and they drop lots of mana pots, I almost never ran out of mana.
All good advice. With or wothout shots, you want mobs you can one or 2 shot. Preferably go for mobs that the shots just barely kill tem, or leave you with one or 2 melee hits to finish off. Your man will last longer this way, and you'll use less shots (if you are using shots).
At level 30 or so, you get skills to help keep you mana charged, and you will rarely need to sit again to re-charge.
Onec you are level 20, get into D gear as soon as you can. I went all the way to 30 in ng gear on my DW, and I was miserable for most of 20 - 30. At 30, I got into mithril robes and a SOL (Staff Of Life), which is really good gear. The Academy robes are also very good.