+1 on some form of a Permethrin product. Spraying the outer part of your clothing is good, especially upper body garments, but for your pants, I recommend also turning the lower leg inside out and spraying there too in case any ticks/chiggers get inside your pants there.
I almost always use a neck gaiter, shemagh or some other item to cover my neck. They're also treated with Permethrin.
One last tip: work on your scent control, and I don't just mean spraying something on your boots before walking to your stand. I mean taking a shower with either a scent killer soap or no soap at all before going out hunting. This is a tip I learned from some hardcore hikers/campers years ago to ward off mosquitoes, and I have found it works.
Mosquitoes track you down by scent first, and by body heat once they're close to you (most people seem to think mosquitoes just aimlessly wander around and jump the nearest body heat, that is not correct). Whenever I make sure I'm controlling my scent, I have almost no issues with mosquitoes. However, when I've been at camp a few days without a shower, they start to hound me -- that's when the Permethrin comes into play; they may be buzzing me, but it will take care of them if they land on me (though they're still annoying).