While researching e-commerce sites and their check-out / shopping cart sections I have found several tips or suggestions that seem helpful. One is to have some sort of progress chart so they know what all is involved and that they will have a chance to confirm their order. This clears up some confusion and keeps your user posted on what the whole process contains. The page should also be clean and all distractions eliminated. The 'next step' button should be clearly identified and there should also be an option to continue shopping. At the end when their order is completed there should be a note thanking them for their order.