Guides help you to line control objects and paths easily in Illustrator. Here's a short overview of the options and how Smart Guides can take it a step further.
A short tutorial on creating realistic highlights in Illustrator using clipping masks. The tutorial covers creating a path, adding a gradient and then creating a clipping mask.
The twirl tool is a great tool that can make complex and eye-catching objects in no time. Here's one way to use it.