Hard to beat Permethrin. Get it bulk concentrated and dilute it yourself, soak your outdoor clothes in it and let it dry. It will last through several washings and will kill the ticks and chiggers when they get on your clothes. It has a very low toxicity to humans but is extremely toxic to cats so if you have cats you might want to consider something else. It is the same stuff that is used in Nix lice shampoo.
Grady