Between the customer and a purchase is your ecommerce site. Here’s the tale of how providing a more direct path between the customer and their purchase increased online sales for a $25B online retailer by $300M per year. The “more direct path” was a single button with the following language:

“You do not need to create an account to make purchases on our site. Simply click Continue to proceed to checkout. To make your future purchases even faster, you can create an account during checkout.”