A problem I see often is many articles discussing minification techniques, headers, etc. to use but completely ignoring the ten-ton gorilla in the room: Bootstrap. Including its monstrous JS and requirement for jQuery, it’s an absolutely massive library that reaches into the hundreds of kilobytes. Foundation isn’t much better (at 150 kilobytes.)
This is why I think people should use Min. Min (http://minfwk.com) is a tiny CSS framework that’s only 995 bytes, and I use it in every website I make. It covers almost every use case that Bootstrap has, and it even has a Bootstrap -> Min conversion page (http://minfwk.com/bootstrapconverter.html.)
It’s ridiculous to talk about saving 20 kilobytes using gzip, strange new minification techniques, image smooshing, etc. when Bootstrap takes up over 200 kilobytes right there.
Disclaimer: I created Min.