I live in central Illinois.  There are lots of small farm ponds around and I would like to be able to fish some of them.  My question is how should I go about selecting them and getting permission to fish them?

You have to approach the owner in a kind and professional way, as to ensure them you will not damage or harm the fishery in any way.  

Hope this helps.

Look for a pond that has been there for a while. Look for one that hasn't been fished, secluded and has a dam with deep water adjacent to shallow water with trees and overhangs. Look for ponds off of the beaten path.

Ask, and ask again. You may ask ten times but once someone says yes, you are in... 8)

And if you do get permission to fish the pond its always good to give them a little gift to make sure you can go back again. Don't go overboard with the gift, some cookies or pie would be good.

If bass fishing, don't keep and tell the owner you will release any bass caught unless he/she would like for you to catch a mess for them.   Even if they don't mind you keeping a few, clean some and offer them to the owner.  Any species you fish for, you should always clean enough to make the owner a mess and offer them to him/her.

You will be surpised at the number of pond owners that don't mind you keeping all the small bass you want because the pond has gotten over populated with them.

I've fished pounds less than 1/2 acre and caught 12 -15 bass, some very nice ones.