Getting enough reps.
The first rep of a new exercise is the most tricky. You are not sure about your form, which muscles to engage, whether you are doing right or wrong. But, as you keep getting more reps in, you start engaging the right muscles, finding the right form and keep getting better.
What we can do for the first few reps and sets is to work with the lightest weights possible. We can make it easier for us to get through the first few sets so that we can add more weight later.
Making it complicated early on makes it unlikely that we would get in enough reps to be good at it.
Of course, this is not just about exercise.