I have to disagree (a little) about downdressing.
As Einstein (probably, it is disputed) said: "Make things as simple as possible, but not simpler." I can say:
down-dress as much as possible, but not too much
The key, in my opinion is not only to down-dress but to dress to emphasize the "features" that
everyone has. It has been said that women's dress are often used to emphasize things we don't have
like small shoulders, breasts, hips.
But there are other feminine clothes which can emphasize things we DO have, like usually long
legs.
In my experience I have seen that I am "ma'amed" more often with a skirt (no MINI skirt, just a knee
length skirt) than with a pair of trousers, even feminine.
The key is, as always, as for native female, to find our own style and use it.
For some of us maybe casual, for others maybe more elegant, every woman is different, so every mtf is different.
marina