Use latest Bootstrap3 instead of 2 with custom breakpoints and grid sizes.
Add the fonts, base css, base js.
Use JQuery 1.9.1 not 1.6.2
Use Response.js and set the breakpoints on the body tag.
Create basic layout HTML structure
Make navigation bar and header HTML.
Basics of phone-sized responsive navigation.
Hide/show site search field using Bootstrap Collapse plugin.
Add some Yes! images.
Style site search in collapsed and open state.
Fix styles of first main nav item after opening site search field
and then closing.