I'm using this as a starting template for almost any project now. It includes sprites, assorted mixins (aka code snippets), file structure, jquery+cycle+scrollto (most usable these days). And, that's it.
You need to have Compass installed for it to work properly.
/sass/libs - all the mixins and libs needed for us.
/sass/_mixins.scss - agregates all those libraries and some common styles
/sass/screen.scss - agregates all .scss files.
I use BEM naming, meaning .block for independent block. .block__element for elements inside that block. And .block_modification for modification of the block.
layouts.css consists of all the columns-header-footer stuff, all with .l-* prefixes. So you know its layout.
States of the blocks use prefix .is-*. For example .is-running, .is-hidden, .is-open.
Hooks for js should use prefix .js-*.