stx's blind looks good for size. I think a 4' x 4' x 6' tall with at least a 4' high door is good for 1 hunter. I like wide swing up windows, but the sliders can keep you a lot warmer. If 2 people are going to hunt in the same blind, 4' x 6' x 6' tall is good. I don't like short doors. Also a good office chair with arms is good, and I like about a 6" wide shelf for the window sills to use as rifle rests, and I put cheap carpet on them for quietness and ease of swinging if you can't avoid a running shot. Carpet on the floor is also good for quietening a blind. Depending on the type of cover, you may want to be just a foot or so off the ground or you might need a tower to look out over low cover and open ground. Tie the towers down real good. They can really move around in a strong wind, and could possibly blow over with someone in them. The best blinds I've set up are in as much cover as I can get and still have shooting lanes. I put them in scrub oak motts and/or cedar bushes to mask their shape as much as possible. Live oaks and cedars are good because they hold their foliage during the winter hunting seasons.
I have never had a chance to hunt out of the plastic blinds eddybo mentioned, but I don't know any reason they wouldn't be very good.
In general, the more comfortable a blind is, the longer hours you will spend hunting.
Hope this helps some, Tom
Texas State Rifle Association Life Member
NRA Endowment Life Member
A big fast bullet will beat a little fast bullet every time