*** See [http://todomvc.com/ comparison based on a simple webapp]. All suggestions have corresponding Yii extensions.
* Use HTML5 and not HTML 4.01, not transitional, not XHTML
** Possibly use [http://getbootstrap.com/ bootstrap] (version 3) or [http://html5boilerplate.com/ HTML5 Boilerplate] (or [http://angular-ui.github.io/bootstrap/ angular-ui] when using angular, use boostrap3 branch) to get a working pre-defined environment including compat-shims for IE, etc.
* Clean URLs