When people are in "buying mode" it is the perfect opportunity to pull out the big guns and really show them what you have to offer. After someone has added one of your products to their cart, you have the following options:

Let them check out with just that product and be happy with the sale.

Offer a selection of best selling or other related products within your shopping cart before they check out, so you create an opportunity to get more revenue and the customer is exposed to more products they may be interested in.

Let them complete the first transaction with no other offers and once they are transferred to the "thank you" page, offer them a special offer or other related products.

The thank you page is something people really pay attention to - after they have placed their order they want to see any important details regarding their order. So you have a captive audience that is in buying mode. It's the perfect opportunity for you to increase the value of that customer (get more money out of them!)

Implementing a thank you page offer doesn't have to be complex, but here are a couple things to think about.

You should create a sense of urgency, so make it a time sensitive special offer.

You should also include customer reviews/testimonials of the products, to help increase the trust factor.

Don't let your customers off too easy, most customers will tolerate (and often welcome if the product is well chosen) a couple of up-sell / cross-sells within their transaction.

If you don't have any other products you can up-sell consider promoting products you are an affiliate of that are related to their initial purchase.

Can you sell a warranty, or support plan? Can you sell something related to the maintenance or up-keep of the initial product they bought? Is the product something they will consume and need to replace again in a certain time period? Sell them multiple items now - offer them a savings for buying 3 or more all at once. Is your product or service related to something seasonal - if so you could remind them to stock up now while the product is available and in demand.

As always, I will offer the disclaimer that you should always test. If you find your sales are declining or shopping cart abandonment is increasing, you may want to pull back a bit.

Put some thought into what products it makes sense to offer and point out the connection for a more positive reception to the offer.