Cross web browser development

Silverlight, HTML5, CSS3, ECMAScript (or Javascript?) jQuery and the open sourced ASP.NET MVC3.  One of the ways to get started is to go over the very through Project Silk web based training at:

Treat as you would a paper book, this series of web articles covers the design, security and maintenance of a well designed web site that can make you money.

Also, make sure to include a process for your website will implement a mobile user presentation.  I have notices a number of new websites that don’t take that into consideration.  Ask yourself: “How often do I view websites on my phone?” 

Even if you are design phone apps like a crazy person, it is still important that you have a well constructed web site.