Mobile Optimization tips

These days lots of sites have introduced their mobile version.I am planning to optimize my site for mobile users how can I do that give some ideas.

The biggest thing to focus your attention is usability. For example heavy layers of drop-down menus, things that require hovering to display etc are a bit hellish on mobile devices. People ( especially developers and site owners/webmasters ) tend to neglect usability as question and that is wrong ! Badly and terribly wrong !
Next thing to check is in GWT ( google webmaster tools ) is how the site is crawled with the google mobile bot. If you have some issues it will show you what's not ok.