Rules of Programming in any Language

1. Write self commenting code. Use variable names that are full words or common abbr. (note that "abbr" is not a common abbreviation)
2. Write comments which remain true even if the code changes. E.g.
   GOOD: if (INPUT_PIN_1) { //Input 2 is data
   BAD: if (INPUT_PIN_1) { //Data pin
   (notice that pin 2 is the data pin, but the code was changed to test another pin instead. The bad comment will lead future programmer to think of pin 1 as data.)
   (notice that this is a bad example, because the constant should have been INPUT_DATA... see Rule 1 above.)
3. Write lots of comments
4. Retain lines of code which are bad for non-obvious reason as a warning to future programmers. Just comment them out and add the reason.