If you want to level up all you really have to do is be active on the site.
The reward is that at level. 20 you can begin adding ad-fly links to your stuff, and you get different titles to choose between from as you level up. :)

Removing Minecraft should help, If you have any more questions, ask me!

The way I got level 20:
- Make a few project posts, whether its a map or a build, a skin or a texture pack, make a few. For every time someone looks at your submissions you get a tiny bit of xp, however after 6-7 months, all those little bits of xp will gather up.
- Make random threads for anything you need or want. This does the same as above but gives you less. You can ask for diamonds if you think your thread/project is good enough which gives you a bit more xp.
- Commenting on threads, being part of the community and more also gives you xp. To be honest, this is simple and you can go around looking for something interesting and just comment!

Thanks that helps a lot

Just go around being nice, you will get to the high ranks eventually

Pretty much what Warlock said. Though there is nothing really to gain but status beside the fact you have to be level 20 before you can use adfly. To sum it up, don't work yourself hard to level up, you will get there eventually.

Submit entries like skins or projects, get diamonds or views, discuss on the forum and gain emeralds

entering contests is the best way to exposure, so you gain more views and possible diamonds, downloads or favorites

this gains XP

You gain new classes and ranks, they're just titles to display like new miner