Sometimes when going back to old code I scratch my head at why I did what I did. From this I learned to always cite example code I used as a basis for what I was doing even if the end code deviated radically from the example code. And I have now made it a habit of reading my own code periodically on working programs. I have sometimes had to rewrite working scripts to add better comments and better methods because I have learned to do things better over time.

I think that has been the best in helping me with my code is to never let working code lie.