Edit - “do it right the first time” defined in the comments.
The most valuable thing I have ever learned in programming is to do it right the first time. I take extra care now to make sure the logic of a program is carefully planned out ahead of time and that the core code is written to the best of my ability. It takes a lot of discipline, but it results in fewer bugs and gives me a sense of pride on the project from the very beginning (which is actually more valuable for momentum). Projects I’m proud to work on make it easier to come back to them day after day. If you’re also interested in becoming a better programmer, I highly recommend checking out these great resources:
Start by reading this: The Pragmatic Programmer. Make sure you read all of it.
Danny Burbol wrote Being a Better Programmer over at Flipcode, a game development site. The article outlines some common pitfalls, mistakes, and best practices. Game development was one of my first forays into programming (and one of the hardest to date) and the mistakes learned there apply to all platforms.
Becoming a Real Programmer by Guy Keren takes a look at 9 brief lessons to learn. I don’t agree with all of them, but there are some interesting concepts.
How to be a Programmer is the popular essay by Robert Read that you need to read now if you haven’t already done so.