What are some good available "cheat sheets" to help better understand?
Cheat sheets do not help understand. They can help you remember, but not understand. The way we perform matrix multiplication is a convention. The convention happens to correspond to linear transformations, working right-to-left. We could have chosen a different convention, but this is the one that everyone uses, so we stick with it. There is no understanding behind a convention. Do lots of exercises, so you remember it easily. There is understanding necessary for linear algebra, but cheat sheets will not help you with that. Lots of time studying and working through exercises will.