So give them the name of a real live person to call. If you use the name of an employee who is no longer there, this could be a problem. Use a fake name. Don't do this if you live in a very small town or in a place where people are likely to stop by and ask for the person. These can be postcards or mailers that unfold or tri-fold.
Direct mail is more costly than other forms of advertising.
But if gives you greater return than other types of advertising. Co-op mailings and inserts work fine. Use headlines, strong benefit text and color. Find out the colors in the rest of the mailing and go differently with your colors to stand out. BUT solo promotions pull better.