For the last, hmm, 6 months I\'ve been reading into Programming in C, I got myself K&Rv2, BEEJ\'s socket guide, Expert C programming, Linux Systems Programming, the ISO/IEC
Go to work. Seriously, find a job for a beginner and let someone with a bigger knowledge guide You (if You have luck) or check the codebase for a useful hints (if You have smaller luck).
In other way, You can start a project for Yourself as some of folks suggested and improve Your knowledge as the opportunity arises.
However, I wouldn't mix both of these worlds - don't start by agreeing a deal for a money - You will probably be prone to under/over-estimating time cost, won't have a good knowledge of bigger solutions, etc. It's better to have someone to guide You or have more time to learn things.
Ah, and btw. - read books (CC2, some design patterns books, "Clean code" are a good place to start with and great reference-books for the whole career) and blogs (You'll know it when You see it).