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 should follow-up every few months.

Offer rebates on selected items. 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. This cannot be done on all of your items of course, but if you are selling an eBook, or software it can double your sales.

Dont forget to upsell your customers. When they're at your order page, tell them about a few extra related products you have for sale that they could just add it to their original order. Add on sales are a must if you want to multiply your sales.

Having an affiliate program is another great way to explode your sales. 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. You can also sell the reprint/reproduction rights to your products, and you could include an ad on, or with the product for other products you sell. You can also make sales for the reproduction rights and sales on the back end product. You could cross promote your product with other business products in a package deal. You can include an ad or flyer for other products you sell and have other businesses selling for you.

When you ship out or deliver your product, include a coupon for other related products you sell in the package. This will attract them to buy more products from you. Send your customers a catalog of add-on products for the original product they purchased. This could be upgrades, special services, attachments, etc. If they enjoy your product they will buy the extra add-ons.

Dont forget to offer gift certificates for your products. You'll make sales from the purchase of the gift certificate, when the recipient cashes it in. They could also buy other items from your web site.

Send your customers free products with their product package. The freebies should have your ad printed on them. It could be bumper stickers, ball caps, t-shirts etc. This will allow other people to see your ad and order. Once someone buys your product and becomes your customer, you need to do everything you can to keep them.