Using both of these methods will help you learn about realities and motivations as well as the details of any issues.
Part 4 of my guide to the ecommerce experience funnel, where I look at the three modes a person goes through when shopping. You need to consider these for a successful product page.
I take you step by step through the primary and secondary design elements you need for a good shopping basket or cart page.
I run down the five things that cause users to struggle the most on ecommerce websites—learned from watching loads of user tests.