When I took my first quilting class as an adult ed. class at school, the instructor picked the pattern (Ohio Star) and told us to make whatever size we needed. I needed a queen size, so bought and cut fabric (with templates) for a queen size. Fast (?slow) forward 10 years and I finally finished it. The points didn't match and I didn't want to send it out to be quilted, so I tied if. We use it on our bed but I would always suggest something small for the first few quilts. In fact I still usually do baby/lap size so I can quilt them myself.
Good luck with your first project