I would add: code defensively. Initialize your variables (either to a sensible value, or an outrageously wrong value) before passing pointers to them, even when you "know" that the value will be overwritten. Check for errors. Always consider what happens when things go wrong, not just when things go right. Any time you find yourself thinking, "condition X is guaranteed to hold, so I don't need to check for it" consider checking it anyway just in case you're wrong about that, or it changes later.