1. When you make your first sale, follow-up with the customer. You could follow-up with a "thank you" email and include an advertisement for other products you sell. You could follow-up every few months.
2. You could upsell to your customers. When they're at your order page, tell them about a few extra related products you have for sale. They could just add it to their original order.
3. Tell your customers if they refer four customers to your web site, they will receive a full rebate of their purchase price. This will turn one sale into three sales.
4. When you sell a product, give your customers the option of joining an affiliate program so they can make commissions selling your product. This will multiply the sale you just made.
5. Sell the reprint/reproduction rights to your products. You could include an ad on or with the product for other products you sell. You could make sales for the reproduction rights and sales on the back end product.
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