I'm in Illinois.
This is so easy to do because Freeprs are very spontaneous types. If you know another Freeper in your area, or two or three, pick a time and a casual place and announce it and go there! Soon you will be getting replies from others in the area. We seem to think once a month, the same week in the month is easiest to remember. The less formality, the better.
I give credit to Chieftain for helping to launch this here.
He's the one who had the motto to " keep it simple stupid."
Good luck!
Recovering ex-hippie has some good suggestions at #10, but some additional steps may also be taken.
You can contact the Central Illinois Chapter of FR Network and see if they hold get-togethers that you can attend.
http://ice.he.net/~freepnet/
If that doesn't work, post something about the meeting that you schedule (or a more general initial inquiry about interest and locations) on the Illinois board:
http://www.freerepublic.com/perl/profiles2?location=61
Also, start a thread about a definite/possible meeting of FReepers in your area, topic would be "activism/chapters." Ping Illinois FReepers (and adjacent state FReepers if you are near a border) to the thread giving details of the proposed get together or asking about interest and suggestions for locations. You can get the names of Illinois FReepers (who have declared Illinois as their locale) by going here:
http://www.freerepublic.com/perl/profiles2?m=member-list;location=61
I suggest that your best option (if Central Illinois doesn't work out) is to organize an event yourself, preferably in a restaurant in a center city or other easily accessed location for FReepers in a wide area. A picnic where FReepers bring their own food is another possibility, as is a potluck event at somebody's house or backyard cookout when the weather cooperates.
(I strongly advise against listing personal residence addresses, email addresses, or telephone numbers in a public board, but you can use FReepmail to communicate those as needed.)
One of the greatest traits of FReepers is their willingness to roll up their sleeves and do what needs to be done, instead of simply waiting for someone else to do it.
Hope that you have a great event!