Havent seen any guides. IMO, the best thing to do is start playing around and experimenting for yourself. A simple way to start is to get a new launcher like Launcher Pro plus, ADW, Go Launcher, etc. They can be found on the market and allow you to customize your phone pretty easy. Most people list the apps they use in the layout/theme threads. Knowledge of photoshop or GIMP is also very helpful, oh yeah, and creativity.