Start with a bootcamp at the park, during the summer and fall. Once it becomes to cold to be outside is a great time to offer moving the training into their homes to keep their success going. This was a successful tool for me and then it was word of mouth after you get results people will brag they have a trainer coming to their home!
Word of Mouth is great! Start with your friends, family..make up some promo materials by using a cheap resource such as www.vistaprint.com. You can bring those materials (business cards, promo post cards, etc) to local schools-leave in their break rooms for the staff members, library bulletin boards, grocery store bulletin boards, email blasts, online posts. Also think about leading small group sessions-maybe contact a local women’s group (or even a church group). Give them a free trial, show em what your all about.
Once you rope in 1-3 people and are successful you should be able to find new avenues to get the word out.