Been in the energy business for 35 years here.
In addition to what has already been said, first get an attorney to look at the lease when you get close.
Other things:
Make sure you are covered for surface damages. Repair of fences, roads, disruption of water wells, animal injuries, etc.
Is the option without any additional payments? Need some more money here.
Most of the shale leases are three years. You are probably over the New Albany which is not as prolific as some of the 'big' name plays but shallower than most. You might ask about the target zone and lease only from the surface to that zone and hold back deeper rights.
The percentage royalty payment is also low compared to what is going on in other major plays; more like 25%. But again the area is not known (yet) to be as prolific.
There are lots of websites out there on shale plays with a orientation towards royalty owners. Do a search on that.
Be careful of how the royalty payments are calculated. Some of the shadier operators have separate companies to gather and process their crude and natural gas (nothing wrong with that) but charge excessive fees (that is where the problem comes in). Make sure you have right to audit the accounting.
Good luck.
Maps: Exploration, Resources, Reserves, and Production - Energy Information Administration
RIGZONE - New Albany Shale Could Create Jobs, Economic Growth in Illinois