Looking to get a fair deal

We are trying to determine the value of an oil/gas lease NW of Caldwell in Burleson County. Anybody know what's a fair rate per acre and a good royalty percentage?

According to my resources:

The average is around $250.00 with the high of $950.00. Royalty varies from 1/6 to 1/4. It just depends on your ability to strongly negotiate, along with negotiation of a very good lease form.