Have you tried telling her why you want her to do these things, or saying what will happen if she doesn't? "Good" doesn't mean much to a child: "good" can be running around playing with a friend or sitting still - both of which are opposite activities. And if you say "be a good girl for mummy" then tell her she isn't good for not being compliant - what's that doing to her self-esteem? She's still good, she just isn't compliant.

Have you also tried asking why she doesn't want to do these activities? EG Liebling doesn't want to get dressed in a morning because it's too cold - so either I help him so it's quicker or he gets dressed under the duvet. Liebling doesn't want his hair brushed because there's a knot in it - it will get knottier if I don't brush it so he has the choice of brushing his hair himself properly, me doing it or us shearing it all off again. I've always asked him to clarify why he is being oppositional, as soon as he was speaking (before that I understood he didn't like it, then explained why I was doing X anyway) and helped him to explain if he didn't have the words.