I just posted this screencast video on YouTube where I critique vector art created by a beginner Adobe Illustrator user. These critiques apply to any vector art software.
I currently have an intern who worked on the vectorization of some of my sketches for recent projects, and after looking over her vectors, I thought it would be helpful for other vector art beginners if I went over her paths point by point (pun intended).
Some of the items discussed in the video are the correct placement of anchor points at curve transitions, best practices for anchor point handles, and a short explanation about why creating your vector paths smartly with minimal anchor points is worth the time to learn to do correctly.
The tips assume you have a basic working knowledge of vector art software and the Pen tool.