What are your “hard rules” about commenting your code?

Question

I have seen the other questions but I am still not satisfied with the way this subject is covered.

I would like to extract a distiled list of things

Answer 1

A great rule for comments: if you're reading through code trying to figure something out, and a comment somewhere would have given you the answer, put it there when you know the answer.

Only spend that time investigating once.

Eventually you will know as you write the places that you need to leave guidance, and the places that are sufficiently obvious to stand alone. Until then, you'll spend time trawling through your code trying to figure out why you did something :)