Sort of a Maslovian hierarchy. I.e. don’t attempt a subsequent step until you get the previous step right.
- Load fast
- Don’t break the browser or the web (e.g. bookmark-ability, back/foward, searchability, etc.)
- Align with core web UI conventions (e.g. use hyperlinks for navigation, use forms for data entry)
- Be consistent with other web apps in your product family if you have one (e.g. all Google apps, all IBM apps)
- Make it pretty and do cool stuff if if it helps your users be more productive and/or have a more pleasant user experience