Some month ago I read the book: Clean Code, I highly recommend it. Here are the best tips that I found.
edit: These are my notes from the book "Clean Code" ,Robert C. Martin. I know that some tips are polemic so I wanted to share it to know what others think about it. You can read clean code articles by Robert C Martin
edit2: I want to share more info about the "less that 2 arguments" and 5 line functions.
The author says: "The ideal number of arguments for a function is zero (niladic). Next comes one (monadic), followed closely by two (dyadic). Three arguments (triadic) should be avoided where possible. More than three (polyadic) requires very special justification -- and then shouldn't be used anyway."
A really good stackoverflow 's thread about the "5 lines functions"