What are some tips/rules for frontend minimalism?

Whether you're talking UI or code structure, functional and elegant minimalism requires planning. Before you start laying down markup or css, sit down and write out what elements your site needs to be functional, where they will sit on a page and how you're going to achieve that layout in plain English. Minimalism in coding falls apart once you have to start adding a bunch of dependencies and exceptions to account for something you didn't anticipate - so make a conscious effort to anticipate!