I could probably continue on long enough to reach the character limit, but then... you know... "tl;dr".

So here's just the first three that came to mind.

1. Never get too attached to your code. Sooner or later, by intention or tragedy, it will be gone. Instead, hold value in the lessons you learned when writing it.

2. Always be experimenting. Don't be afraid to try new languages, frameworks, technologies, etc. However, when it comes to projects intended to eventually reach production, stick with what you already know.

3. Ask questions whenever you have them. The explanation of your ignorance can sometimes alone be enough to shed light on some related technical paradigm.