How do I get a word out that im babysitting?
You can also try looking up "Mom Groups" in your area, then just let them know... there are a ton of support groups for moms out there, they usually give you ph# or email address of who you can contact to join, but it doesn't hurt to call them and let them know your services are available too.
if you've already done some baby sitting, ask them if you can use them as a reference, this always helps everyone with kids wants a good babysitter.
Put an ad in the local newspaper. And theres sites like http://www.kijiji.com/ where you can post that type of thing.