So we've done all French sites before. And we've done all English sites before. But a recent project was our first real forray in to multilingual sites and it's an e-commerce/Ubercart job! Talk about gluttons for punishment!

There are bags of tutorials, so I'll keep this short but sweet. A list of dos and don'ts from our painful, recent experience:

1. Don't change the default language after initial set-up. Set your default language right at the start and don't mess with it. Ever.