If you can, use thick bars and avoid straps. When I get really into grip training I use my captains of crush hand grippers, do isometric holds from a rack pull, put rubber bands on my fingers and stretch them out, and of course the good old fashioned reverse curls and wrist curls. I think it also helps to squeeze the barbell as hard as you can (I think I read that from Dave Tate). Farmer's walks are nice too but I don't know how applicable that will be for you. I wasn't blessed with popeye forearms like my brother even though we both wrestled.