On the Toptal.com site they've posted a guide that aims to help you write good code that stands the test of time. They provide six "commandments" that they think can help make your code better and easier to maintain in the future.

Specifically, “good code” is code that is easily and readily maintainable by an organization (not just by its author!) and will live for longer than just the sprint it was written in. The following are some things I’ve discovered in my career as an engineer at big companies and small, in the USA and abroad, that seem to correlate with maintainable, “good” software.

Their list includes suggestions like:

• Treat Your Code the Way You Want Other’s Code to Treat You
• Good Code Doesn’t Reinvent the Wheel, it Stands on the Shoulders of Giants
• Don’t Cross the Streams!
• When Possible, Let the Computer Do the Work

Each item on the list comes with a brief description with a bit more detail and how to apply it to your development. It's not focused on any one language, however, so there's no code samples here - just links to other resources and tools that can help in their application.