Learn How to Code this Weekend. Programmer 101: Teach Yourself How to Code. Learn to Code Epilogue: Best Practices and Additional Resources. Great post.
The bit about comments being even for yourself 6 months from now is so true it's not even funny. Just to clarify (and further stress) why eval in JavaScript is evil: It's not that it just treats a string as a variable per se; it attempts to *execute* any string as JavaScript code. This means that you could put anything that would run in JavaScript into a string, throw it into that function, and it'd run.