When you feel the need to write a comment, first try to refactor the code so that any comment becomes superfluous. - Kent Beck

Optimism is an occupational hazard of programming: feedback is the treatment.

When you find you have to add a feature to a program, and the program's code is not structured in a convenient way to add the feature, first refactor the program to make it easy to add the feature, then add the feature.

Often you'll see the same three or four data items together in lots of places: fields in a couple of classes, parameters in many method signatures. Bunches of data that hang around together really ought to be made into their own object.