Keep yourself informed
As a web developer or web designer you need to inform yourself about the latest news and tools available. A few weeks ago I found this cool show named The Treehouse Show presented by Nick Pettit and Jason Seifer.
In the first episode they talk about Responsive Web Design as well as several CSS and JavaScript tools. Also in the first episode they are talking about Twitter Bootstrap.
I posted the first episode here, I suggest you to check the others too because I am sure that it will help you as it helped me too! Check their youtube channel, they have a lot of tutorials related to web design and web development.