A frequent question in babysitting forums is what should be included in a flyer. Flyers can be posted on the bulletin boards at Wal-Mart, grocery stores, public parks, libraries, universities, and any other local places that allow the public to put up flyers and business cards. Avoid telephone poles or other things that you are not supposed to post in, and do not put flyers in private mailboxes, because it is a federal offense.
A great website that helps you put together a babysitting flyer is Babysitting is my Business.
Also, some babysitting courses include with the "tuition" a babysitting kit, that has a flyer template in it. A great thing about babysitting courses are that you not only get the flyer to attract parents, but you have certification to show that you know what you're doing!! One course that includes the flyer is BabysittingClass.com.
Make sure that everything on your flyer is accurate and truthful. Don't be afraid to brag! Let them know if you've had more than 3 years experience, CPR/First Aid training. Tell them what age groups you work with, leave your first name and a phone number. Give basic availability, i.e. "weeknights and weekends" or "Fridays through Sundays."