I was 19-20 when I first got to the Ozmone plains as well. I wasn't quite strong enough to mop up the monsters in the giza plains but they weren't that bad. Just the elementals would cause too much trouble to handle. When I got to Ozmone I could only handle small groups, but when I got to jahara (sp?) and bought all new equipment it was a cake walk through those areas including golmore, henne mines, and the Paramina Rift.

Paramina Rift is where I'm currently at I just left Mt Bur-Omisace and my characters are between level 22-24. I also only had minimal trouble with the first demon wall even at a low level, I just took about 6 tries and had 4 of my characters with quickenings. So, I agree with the guy who said you shouldn't level up. It will make the game too easy for you. Unless, you want it to be easy of course.