Practice speaking in Keigo, teneigo, tameguchi?

I’m pretty good with teneigo (です). This is because that’s what I’ve practiced since starting to learn JP.

I want to practice tameguchi. But now that I’m practicing it, when I try to speak teneigo, sometimes tameguchi comes out.

How do people train this?

My current idea — to have a priming phrase and to only practice each one separately and never mix.

Advice is appreciated.