I feel that I am good at writing code in bits and pieces, but my designs really suck. The question is how do I improve my designs (in order to become a better designer). I think schools and colleges do a good job of teaching people as to how to become good at mathematical problem solving, but lets admit the fact that most programs taught at school are generally around 1000 - 2000 lines long, which means that it is mostly an academic exercise and no way reflects the complexity of real world software (a few hundred thousand to millions of lines of code).

This is where I believe that even projects like topcoder/project euler also won't be of much help, they might sharpen your mathematical problem solving ability - but you might become a theoretician programmer; someone who is more interested in the nice, clean stuff, and someone who is utterly un-interested in the day to day mundane and hairy stuff that most application programmers deal with.

So my question is how do I improve my design skills? That is the ability to design small/medium scale applications that will go into a few thousand of lines of code? How can I learn design skills that would help me build a better html editor kit, or some graphics program like gimp?