A number of vendors would be delighted to sell you their ready-made "frequent touch" prospecting programs. Such programs usually consist of cards, newsletters, and a calendar. When you examine the details, you learn that you can buy several levels of program: monthly, bi-monthly, or quarterly.

The magic number depends on the individual, but many experts recommend 5 to 7 contacts each year. In the case of the ready-made prospecting programs, the middle ground - alternate months - should work well.
However, you should not rely solely on ready-made programs. They're informative, but rather impersonal. So, plan your own prospecting program to include face-to-face contact, phone calls, and e-mails. You could, then, select the least expensive ready-made program (just to give your prospecting some consistency), and supplement that with your own personal contact, to achieve the desired number of contacts each year.