You should include your signature file with all the questions you answer by e-mail. Your signature file should be no longer than 5 lines, 65 characters per line. Include your contact information, business name and an attention getting headline.
Tell people about the new products and services that you right on the main page of your site. Have a special section on your home page specifically for new product announcements. If they have already bought products from you in the past, offer them add-on or backend products.
If you're using FAQ "Frequently Asked Questions", include a text ad or link on top of your FAQ site. You could also include a subscription form for your free e-zine on the site as well.
When you answer peoples questions by snail mail, include an insert advertisement for the products or services your business offers. Include your web site address, e-mail address, logo, slogan and other information on all marketing material that you send.
Your customers will always have question so you need to always refer them back to your web site. Keep adding to your FAQ’s section and you will become known as the expert in your field. This will surely increase your visitors and your earnings.