Multiply your marketing and advertising efforts on the Internet. You can accomplish this by starting an affiliate program, using viral marketing or both. For example, you could start an affiliate program and give your affiliates customized e-books with their own affiliate links to give away.
Increase your ratio of visitors who purchase your product(s). You could change your headline, offer a stronger guarantee, add testimonials, etc. For example, one week you could have your headline say, "How To Lose 5 Pounds In Two Days!" and
the next week use, "Lose 5 Pounds In Only 48 Hours!" Just see which one pulls more orders per visitors.
Find out who are your strongest leads for buying your product by offering a free e-zine. The visitors who are very interested will subscribe to it. Once they have subscribed, you can sell them related products again and again. Just make sure your e-zine has enough original content to keep them interested...