I made the exact mistake Bob mentions in the video! My gray wasn’t quite gray enough, and it turned to green in the clouds. I did upgrade my brushes and paints from bargain versions. The better quality brushes definitely felt easier to control, and using the same colors as Bob did make it easier to follow along. Using the knife to make the dunes in the foreground was very difficult for me, that is a technique that will take me a long time to feel comfortable with.