You can tell her what you don't like about her "hair methods" without actually saying it to her directly. If the topic of hair ever comes up, tell her all of your ideas & the things you've learned since going natural. Tell her the things that you're against, and what you don't like going in YOUR own hair. By doing this, she'll get the picture & understand what you don't like. That should solve the problem of her putting products in your hair that you don't want at least. She probably won't agree with what you have to say, but at least you were able to get it off your chest without offending her.