This article “Make your WordPress powered Website load with Lightning Speed” is a comprehensive discussion that starts with the Why and then goes on to give you a long checklist of items to review for your site. Even if all aren’t applicable, this page is a great res
40+ Free Responsive WordPress Themes. Some good starting points for your mobile consumption. I witnessed “bones” made into a cool site, with a bit of work. Using a basic framework like that one, lets you learn the basics and gets you running in minimal time as well.