There are several things you can do, there are a few products that repell ticks, like deet (I've read that it is not that strong against ticks) and Permethrin (to spray on clothes) that kills ticks on contact.
There is also tick repellent clothing (Permethrin) that you can buy, it lasts up to 70 washings.
Best protection is said to be deet on the skin, and Permethrin on the clothes.
I read that teatree oil repells them too. I use it for mosquitos and fleas. The smell is a bit strong, but applying deet throughout all summer can't be good.
Have a look at this study about tea tree oil and ticks:
http://www.ncbi.nlm.nih.gov/pubmed/15817219
MarieLS