to be good core coder

First off you said you wont bite! second, who am I? I'm an Egyptian guy, started learning php recently, and made a little content management script (in Arabic located at dev.dd4bb.com) it functions good, but it is not extendible, I did not try to make it do more functions, but I'm sure (specially when I'm trying to read the source files I have written) if I want it to do more, I'll rewrite most of the code from scratch. and here comes my question, how I can improve my core coding, by core coding I mean how I can spread my future sight when I start writing new application! and make my mind more widely opened for future needs. I know my question is a very general and can't be answered by an Email, but I thought I may try to ask, and you may just give me some useful links to some tips and advices (or even books)... thanks for your efforts.