I've rounded up some of the many articles we have written on various aspects of checkout optimisation into one handy list.. 

For more detail, see our recent Checkout Optimization Guide, a must-read for all companies that accept payments online.

Mistakes to avoid

Is this the most hated checkout process on the web? 

A look at the cross-selling usability nightmare of the GoDaddy checkout process.

Overcomplicating the checkout process 

Another example of checkout worst practice. 

Checkout optimisation tips for Virgin Media 

Some suggestions for Virgin Media on how it can improve its checkout process. 

Discount codes

Dealing with discount codes in the checkout process 

Are discount boxes costing online retailers in terms of lost sales, and how can they handle this? 

Trust, information and payment security

Does your checkout process answer customers' concerns? 

A look at the kinds of information and reassurances that customers need during checkout. 

E-commerce trustmarks: do they matter? 

How important is it to display third party security logos? 

Why good checkout design is more important than trustmarks 

Design factors that help build customer trust. 

How do you handle payment card declines?

Matthew Curry looks at the options for handling this issue without losing a sale. 

Verified by Visa: a conversion rate killer? 

Verified by Visa has been adopted by many online retailers in the UK, but does it cause customers to abandon sales?

Checkout / basket abandonment

Should you be emailing checkout dropouts?

Reminding customers about their abandoned baskets can be an effective way of tempting them back to the purchase. 

Checkout error handling

Is postcode entry costing you conversions?

Why strict postcode validation should be avoided. 

How to handle checkout errors

Some general tips on error handling and messaging. 

Registration

Why you shouldn't make users register before checkout

Includes the example of an e-commerce site that added $300m to its annual revenues simply by removing the register button.

What is the best way to handle registration?

A look at some of the options. 

Which retailers are making users register?

Plenty of retailers still insist on customer registration though, despite the potential for reducing abandonment rates. 

Interviews

Checkout Optimization tips from Dr Mike Baxter

Checkout expert Dr Mike Baxter talks about recent trends in e-commerce checkout design. 

21 e-commerce experts interviewed

A round up of e-commerce related interviews from 2009, including plenty on checkout design.