I used to be so frightened to cut too. Then I agreed to be a quilt pattern tester. You only get so much yardage so you have to be careful. I would measure at least twice before cutting and I labeled everything. You will get comfortable.
Suggest you join a quilt guild in your area. You live in a beautiful area and is it quilt crazy!! You have the headquarters of Quilting Newsletter in Golden and McCalls in Boulder. My daughter lives in Littleton and I envy her - beautiful country and lots of quilt resources. Talk to the ladies at the Rpcky Mt. Quilt Museum in Golden. They will have some good advice for you.