You can spray with Permanone (permethrin), or you can buy clothes from Gamehide. I bought pants and shirts last year and have not had a tick while wearing them. The fabric is impregnated with permethrin and is claimed to be good through 70 washings. We'll see.
I have no interest in the company, but thought I would pass along the information. The stuff is pricey ($70 for pants, $50 for ls tee). It's worth it to me, because I'm out with the dog twice every day.
BTW, I'm told you can freeze ticks for an indefinite period and they will survive. My entomologist hunting partner says there is always some species of tick active, regardless of the season.
Richard