Not so much on the looks of the outfit, but..

Make sure you get out and 'run' whatever outfit you might consider taking on a hunt.
Make sure the clothes work for you and your style of handling your rifle.

For instance, I just don't do well with big pockets on the front of my hunting shirts, especially if they don't have button or zip flaps. I find the butt of my rifle can catch on the open mouth of the pockets and that makes things a pain in the ass for me. I wouldn't want to get out on a hunt across the world and into the brush to find that my gear got in the way of my hunting.

Know what I mean?

Test drive your gear on a hunt at home and take notes on how it works for you. If you think you'll be carrying binoculars or using sticks, pack that stuff along with you on your local hunt -- and use them. Do some fast reloads from your ammo belt or pouch, drink from the canteen you want to take, tromp around in the gaiters and break in the boots. Find out before you head out on your big safari.

--Tinker