Well, in the books the only known defense are psychic shields, like when Harry tried to defend his mind by putting a “wall”, and that was revealed to be the default WC answer to defending minds.
Other than that, unless your character is mostly instinctual, and doesn’t think, just acts quicker than than MindMage can react, I don’t believe there is a way to stop them... also I’d love to learn more about the Dresden Files RPG, I just recently learned about it, so if you could help me out, that’d be pretty cool! And good luck with the issue, I hope I helped!