Practice, practice, practice. Then practice some more. Teaching the art is just like learning the art. The more practice, the better you get. I'm in the same boat.
True, with a caveat.. Practice makes permanent. Practicing errors makes a person really good at making the errors. Practicing good fundamentals cuts down on errors and makes practice more productive.
"Here's what I think sensei does" or "Here's why I think your movement is failing, and if you change it this way (woops) see how much more easily you throw me"
as another has said - try to avoid "don't"