I'm a newbie too. Consistency is the key, I think...In quilting, they speak of a 'light 1/4 of an inch', and such....JEEZ. Im just trying to maintain 1/4 of an inch....If you line your fabric's edge at the outer edge of of your machine's foot, you should be GOLDEN!
As long as you're consistent, everything will line up! The cut and the press are also critical. I've had blocks go amok, only to find my press was off. It doesn't take much. I have the best results with pre-cuts. My cutting is a little off, and it probably doesn't help that I learned what I know from two lefties (YouTube and Craftsy tutorials). I'm retraining myself, regarding cutting, with Carol Doak's book 'Your First Quilt Book'. She addresses this in her book. LOVE my lefty mentors, all the same!
But accurate cuts are critical....