Buy her books where the heroine is female and achieving things other than being pretty.
Let her do any sports of play she wants to, including those which are dominated by and associated with, boys. Fight for her right to participate in those activities. Don't let other people persuade you that it's too much trouble to include her.
Let her have her hair short if she wants and wear "boy's clothes" and tell her they're not boy's clothes, they're her clothes and she's a girl, so they must be girl's clothes.
Expose her to female role models who are not doing stereotypically feminine things: car mechanics, engineers, pilots, sportswomen, police officers, bus-drivers, doctors etc. Let her know that she doesn't have to limit her dreams or life, because she is a girl.
Find out and tell her about women from the past, whose history has been erased, who achieved incredible things in the face of male obstruction - Dr James Barry who had to pretend to be a man to practice medicine (and who the transborg is trying to appropriate), Marie Curie, Ada Lovelace, Elizabeth Garrett, Edith Cavell, Josephine Butler, Annie Besant, Eleanor Marx, Julian of Norwich, Bess of Hardwick, etc. etc. etc. etc.
Stand up for her right to be different, to be a girl who doesn't perform femininity.
Be prepared for the possibility that she will be a lesbian when she is older. Most gender non-conforming kids if left to their own devices, will grow out of it; a small minority become lesbians or homosexual men. A large number of those are about to be horrifically abused by homophobic parents who would rather account for their children's gender nonconformity, by explaining it as the child being born in the wrong body, than accepting their children for who they are.
Google Stephanie Davies-Arai, who runs a site for parents with GNC kids (gender non conforming) and supports them to allow their children to be who they are.
Learn about feminism. Introduce her to feminism. It will allow her to be herself, which is what you want for her.
Enjoy her uniqueness. 