The answer is pretty simple.
There are so many.
The first one is to make sure you understand the concept of an instructor and how they are supposed to teach the basics of swimming.
Then, there’s the ability to learn in a safe environment and be able to focus on the swim itself.
Then there’s understanding that the sport is a physical activity and that there is nothing inherently wrong with a little swimming.
A lot of the other basics of how to swim are just as important.
You need to know how to breathe, how to keep your body stable and how to balance, all of which can be learned from a good instructor.