Many visual designers only show the final product. They don’t show the work that went into it. They should. It would prove that you rarely get good visual design the first time.
More often than not, quality is the result of many attempts at something.
First, this is true when you need an idea. Ideation. Come up with as many ideas as you can. Use those ideas to inspire other ideas. Don’t stop until you have to. The best ideas rarely come to you first.
Second, this is true when you have an idea and want to improve it. Iteration. Most people don’t iterate enough. They stop when they’re happy. Good designers don’t stop when they’re happy. They stop when it’s perfect. “I’m happy with this” is different from “there’s nothing I can improve about this”.
Iterate more than you think. Fifteen times at least. This is easier if you get feedback. Show your work to a good visual designer. They’ll point out problems you can think about. That will give you the energy you need to improve.
Third, this is true for practice. Create as much visual design as you can. You will improve faster. You will feel more comfortable. Parts of the skill will become second nature. You won’t have to think about them any more. You can think about more important things.
Pick a random joke in your script. It can even be one you like, and imagine you’ve just been told that the only change you need to make is to improve that joke. I bet you can do it. Now do it with every single joke in your script.