Anytime I find a mission or dungeon its always +2 or something. Practically impossible.
After I were on a certain level, I went to a lake what had spitters and crabs spawn all over themselves, they were my great source of "grinding" because each monster granted me 5 XP, you should try to find some signature places after you have aquired just a few levels.
Tip: If you look at the minimap, search for places which name's are white or light blue, because they mean they are the same level with you or a little bit higher, I think. Also, NEVER go to areas with red text, because when I was lvl 3, or something, I found "Arurok Canyon" what was labeled with red text, and even still in my day now, when I'm 19, it still is labeled with Red text (= means many levels higher than you).
EDIT: Just read the getting started:
http://www.cubeworldwiki.net/index.php/Quick_Start_Guide