I was scared too until I started. I did make a small 9" x 12" mock quilt that I sandwiched together for pre practice. I had made a small baby scrappy quilt to use as practice, and then decided I needed practice before my practice quilt.
I tried several different things on the time one, then took a deep breath and did the scrappy. I did take out a few of the mistake stitches as I went along, but it turned out just fine.
You can do it!