I spend a lot of time in the field, both at work and scouting, and on summer outdoor activities.
The formula that we find works the best is a multi-stage approach.
Get a set of clothes that are light weight and light colored. long pants and long sleeve shirt, treat the clothes with Permethrin spray. (available through lots of retailers) Apply to the clothing only, follow the directions, and this will last far quite a while, and through at least a couple of washings (they claim). Wear these clothes whenever you are afield.
I also spray my ankles and claves, waist line, lower arms, armpits and neck, ears and head with 100% deet spray.
Keep your shirt tucked in, tuck you leg cuffs into your boots (or tape the cuffs), and you now have a two phase layer of protection ! The Permethrin will stop them from crawling on you , and any that get through to your skin should be repelled by the deet.
I am going to treat my light-weight camo outfits for early bow season this year with the Permethrin to help protect against the ticks.
Good luck !