I'm going to generalize, when I taught something like differential equations, matrix analysis or complex numbers, the issues with explaining and transmitting knowledge in a way that flows is hindered (at times) when the students lack or barely understand the foundation for whatever concept you are teaching.
Math concepts are progressive and incremental, meaning that lacking a basic skill or concept harms understanding the next. Many times it's not what/how you are explaining, is making the assumption that the foundation to understand a given concept is there when sometimes it's not.
In Engineering school I had a lot of professors who were great Engineers but horrible teachers. The number one issue that I had with them was them not knowing how to review or introduce a given concept.
When you teach art, many times you have to introduce some context to understand a concept. The same applies to math, only that the context is something that is supposed to have been learned and practiced; it's more implicit.
They way I used to explain math when I taught it was showing some practical application when I could find it (There were many things that were more applicable to developing the analytical skills, not directly applicable knowledge per se). As I explain a concept, I give an example, show step by step how to arrive to the solution, explaining in each step what is needed to know from previous math material. And then repeat, repeat, repeat. I give a few classroom practice exercises and discuss them, them leave them on their own and hope I gave a good class.
