I use word of mouth, magnets on my van (just got a client last week from my nephews preschool because her DD goes to his class and she saw my magnet), hand out business cards like crazy, tell my friends and family and they tell their friends and family, craigslist, google directories, care.com, and I have a website which I list in my google directory.
I think the majority of my calls are from people that google for child care near their area because of a combination of my free basic listing in the google business directory (have to list your address) and the link to my website. They google, see my daycare, see the link to my website which has all of my information and go to it, read the info and then call me for an interview. The more they know about you the better the chance you get of having them be more interested in you and call.
I have also had luck with craigslist by making a cute flyer and attaching it to my ad. You have to make it stand out. For example, here's mine:
My current CL Ad
And yes, you will get ALOT of spam or fraudulent emails but just ignore them. If you aren't sure if it's legit or not just email them and tell them that you only accept american personal checks or cash. If it's fake you won't hear from them again
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