Long time ago when I was a kid I worked with a Block Layer named Bobby Muncie. He taught me how to lay block. When he was teaching me he told me over and over and over again "You practice doing it right, speed will come." I have applied that to almost everything I do in my life.
The best way I found to practice reloads is to just do it over and over and over again.
Especially when I was working nights. I would put a towel on my desk and unload my gun and just change magazines over and over and over and over again until I could do it my sleep.
Then when I went to training I never topped off My magazine in class. Is simply reloaded my handgun as needed during the course of fire.