Ask the questions and digest the answers. Beautifully written blurb sent to the wrong people will end in the waste paper basket, and lose money. The best list of names and addresses is the one you have carefully compiled, checked and cleaned of all duplicated or out of date information. Much will depend upon the market. Every book has a limited appeal, the trick is finding those to whom it appeals.
Direct mail does allow gut reactions to be tested, again and again.
Small test mailings to groups of people who may be interested. Responses will come from unexpected quarters, this is part of the fun, but be prepared to recognise and accommodate these new opportunities as they arise. Present contacts Existing customers and contacts are the best place to start. As you meet new people they should register as potential buyers. Read articles with that in mind, noting interesting names.