Blisters are caused by friction. This implies that your shoes aren't fitted properly. Are these new shoes ? Were you fitted for them at a reputable sports store ? If you just bought them because they seemed to fit okay in the store, then you may want to consider returning them if they are new. Properly fitted shoes should not cause blisters. I had a pair like that. fit right in the store, but when I started using them, they caused blisters. I couldn't return them, so I ended up donating them to the Goodwill since I really couldn't wear them.
Also, how did you tie your shoes ? Some times, improper lacing can cause the shoes to slip and cause blisters too. Oddly enough, there are different ways to lace shoes. www.sierratradingpost.com/lp2/running-shoe