T.F.
Make sure you get permission for your flyers.
We had flyers for a cheer clinic through the school and we still had to go through the process of everything being "ok'd" before it was allowed to be available in the schools.
Make sure you are ok'd by the city to leave flyers in the library, rec centers, etc.. You may leave them and then go back and realize they were pitched in the trash for not having the proper permits..
Talk with preschools.
It is late in the year right now but in the beginning of the school season, many PTA's sell advertising to help offset the cost of the directory publication. The cost is nominal.
Again, it is a little late in the year but some PTA's have fundraisers in the spring with silent auctions, etc... check with PTA President's at your local schools for info.
How about your neighborhood? Ours has a secure website. You can pay a nominal fee and advertise on this website.
I don't know if this would be efficient or not but are you on Linkedin.com.. It is a professional networking site where many people are posting about jobs, opportunities, etc.
Good luck