This is a small change that will make a big difference. Use it everywhere. Replace the words 'don't forget' with the word 'remember'.
When you say don't forget, your brain hears two negatives. The focus is negative and it is on forgetting. Usually this actually makes us forget. Have you ever told your child "Don't forget your lunch." and then they forget it. Try using 'remember' instead.
Here are some examples of how to use this on the course.
Change "Don't chunk it in that tall grass." to "Remember to swing through the ball."
Change "Don't top the ball." to "Remember to keep your head down."
Change "Don't end up in the water." to "Stay in the middle, this is a huge fairway."