I considered writing something exhorting prospective developers to do various things. I considered describing what I expect and demand, as someone who hires (and, disappointingly often, fires) developers. I considered advising people of certain ilks and descriptions to pursue other professions. In the end, though, I decided simply to share this now-classic link, and encourage everyone in this thread to read it:
http://www.codinghorror.com/blog/2007/02/why-cant-programmers-program.html