Another thought is in how and why you ask her to do things for you, such as in the way she dresses. Women can be very sensitive about these types of things, and if she gently resists, and you keep asking, things will only get worse. Women who feel loved and comfortable will do just about anything within reason to please their man sexually, often they will seek out ideas from other women, magazines, or they will just come out and ask. The problem lies with how they perceive the situation, and your reasons for asking. They want to be loved for who they are, and in turn they will seek to please you, but if they think that you need to dress them up or have them perform in a certain way because they don't feel that you are otherwise attracted to them, you're heading for trouble.
Sexuality can be a very fine line with women.
I also think you're asking for trouble if you drop some hints of how she may better please you. We just don't see things the same way as women. The Lessons Children Learn. How the Co-dependency Movement Is Ruining Marriages. How to Find a Good Marriage Counselor.