"There are a couple of things that may or may not help," Thomas Snyder says:
Lesson 1. "Don't write anything in the grid unless it's a certain digit. Don't write any notes. Try it with a harder puzzle. See how far you can go. Push yourself."
Lesson 2. Slow down. "Trying to solve it fast is not the end all and be all. You should get enjoyment from it. Only for a rare few of us is it a career."