#Write an explanation of your code
Writing an explanation forces you to thoroughly look at each part of your code again and to make your thoughts and choices in writing a certain passage explicit. In doing so, you might find that different approaches are possible which may save some bytes, or that you subconsciously made assumptions which don't necessarily hold.
This tip is similar to Question your choice of algorithm and try something entirely new; however, I have found that the step of actually writing down how each part is supposed to work is sometimes crucial for becoming aware of alternatives.
As a bonus, answers including an explanation are more interesting for other users and are hence more likely to be upvoted.
