I am currently at Future of Web design Conference and was fortunate enough to attended a workshop with Jason Pamental called From Sharpie to Sublime: A Responsive Design Intensive.
It really opened my eyes to a lot of things, especially the unknown-unknowns such as simple best practice like wrapping an image tag with a figure tag and why we should be using EM’s and not PX unit measurements as newer mobile browsers display based on the pixel density rather than the actual screen width thus breaking our websites. Highly recommended workshop.