If you don’t make mistakes, you’re not working on hard enough problems. And that’s a big mistake. ~F. Wikzek
It was when I found out I could make mistakes that I knew I was on to something. ~Ornette Coleman
While one person hesitates because he feels inferior, the other is busy making mistakes and becoming superior. ~Henry C. Link
I consider myself lucky, in every place of work I had a mentor that helped me improve and taught me something that made me a better software developer. 
Looking back I realize that most of what I’ve learnt I learnt because I made a mistake and someone was able to catch it and show me how to do a better job.
Not all software developers have the benefit of a mentor, either because they work alone or because their code doesn’t get reviewed or simply because no such person exist in their place of work.
In order to become a better software developer one needs to learn how to do so by himself. Reading blogs is one possibility as well as learning from mistakes others already made.
I have two sites I read daily that show mistakes and errors done by others and over time I’ve leant quite a lot from them:
- The Daily WTF – I really enjoy reading this site, It has coding errors and funny stories about our industry. It taught me a lot on what not to do as well as common pitfalls in software projects.
- Unmaintainable code – an extensive glossary of how not to write good code. Just read it and do the exact opposite.
Both sites are a good resource of mistakes done (over and over) during code development that can be avoided by understanding the reason they were made and why we shouldn’t do them again.
Helper Code 