Someone once taught me a phrase I often use "Lowest common denominator coding." What it means is that you should code to the most common abilities held by the group of coders you are working with.

In practice what that means is when you are writing a piece of code you should do so in a way that the new hire fresh out of university with less that a years real world experience should be able grasp what you are doing fairly quickly.

Abstractions, using the latest and greatest additions to the language you are using and obsessing over reducing the code line count can help the code run faster, but it also increases the learning curve for people looking at the code for the first time.