Erm, we're going to need a lot more information (how unlevel is it, are we talking a steep gradient requiring earth moving machinery, or just pits and hollows, how big is the area, etc) and preferably, photographs...

I did suggest photographs Sarah! If you need help uploading some just ask.

Best way is to get a contractor in -- end of problem

The questioner asked this first on a blog and was looking for the most economical option.

Check this out, Sarah:
http://www.buildeazy.com/waterlevel.php