Ehrmigerd!!! You want to be a Mhernir!!!!
Well you're in luck because this is incredibly easy to lvl, just time consuming. There's 2 ways of doing this, both work, one takes an eternity.

The first method is to just simply grind it out all the way to 50. Like I said, an eternity.

The other way involves leves. Grind MIN up to 20 at least, you can go further if you want, then start hitting up those levequests.

Levequest locations is as followed:
20 & 25: Quarry mill
30: Costa Del Sol
35: Coerthas-observitory
40: Coerthas-that other spot with leves just south of stone vigil, name escapes me I'll fix this later ^^'
45:Mor Dhona

I recommend doing each leve at 1 lvl above yours. Little bit extra exp and minimal challenge. Took me just over 100 leves to lvl from 20-50 using this method. Again, you can wait to use leves until your a bit higher, it's actually recommended to wait til 30 to start using leaves, but I was feeling lazy lol. Happy hunting.