I recently was working on some icons for a client and was looking for some advice online. There are plenty of tutorials and programs, but nothing about the creative process — until I came across Denis Kortunov's article at TurboMilk. Here's an excerpt:

Icon design is undergoing a transitional period. On the one hand, screen resolutions are increasing, hence enhancing icons. On the other hand, we still have good old pixels. Icons sized 16×16 and even smaller are still widely used. And so, here are the most commonly observed mistakes in icon design…

If you're designing icons, 10 Mistakes in Icon Design is a great article to read before you get started.