A few notes I keep close:

• Make it work, make it right, make it small. In that order.
• If you cannot explain the seam, you do not have one yet.
• The best test reads like a sentence about behaviour.
• Delete more than you add.

Simple is not the same as easy. Simple is the thing you get after the third rewrite, once you finally understand the problem.

Why I keep coming back to small, durable software, and what "durable" actually means when the ground never stops shifting.