Cynthia, I am nervous about using a rotory cutter too. I got on the Live Chat one night and had a great discussion with the ladies.
A lot use scissors and some never use a rotory cutter at all. They said to use what you are comfortable with and get started quilting.
They recommended practicing on scrap pieces of fabric till you get comfortable using the cutter.
Their big thing was have fun and cut what ever way you want to and keep practicing.
Good Luck
Carol from NC