I always practice naked.
It helps me keep an open stance.

Actually, when I'm getting things tuned up and making adjustments (including broadheads), I'll wear clothing that does not interfere with the string or grip. Once everything is humming along just right, I try shooting again with hunting clothes to insure all is still OK. THat way when I'm getting set up, I know any errors are from the equipment or me, not the clothers. One less variable to deal with.