As @wedapashi already stated, permethrin is a very good choice. And even though it's an insecticide, I find it works well as a repellent also. I treat all my clothing (even socks and underwear) and gear. I can't even remember the last time I found a tick on me. Even keeps the mosquitoes away.
Once dry, it's safe for all animals (except insects).
Permethrin is not new. It's a synthetic version of what's found naturally in marigolds (pyrethrin). It's currently used by the military when washing uniforms, and also sprayed on orchards and farm livestock.
You can buy it in small aerosol cans ($$$), or buy it concentrated on Amazon ($) and use a garden sprayer to dilute & apply it.
I would avoid using DEET if at all possible. DEET is toxic even to us. If you do use DEET, don't use anything greater than 20-30%. Higher concentrations DO NOT provide more protection, but may melt any plastics you have on you, and/or remove any paint (latex) that may be hit when spraying.