If you can concentrate on a small geographic area to start, I suggest calling the schools individually to get the names of the decision-makers. It's a time-consuming process, but considerably less expensive than renting a mailing list. Then you should make cold calls to them and follow up with literature by mail or e-mail or, better yet, a meeting. If you are unhappy with the initial results you get from cold calling, you can send letters first and then follow up by phone. And if you are trying to reach a very large geographic market, such as your entire state or a nation, then you should contact a mailing list broker to find the right list and create a direct mail campaign.