How to make her happy by ing better?

That won't make her happy. You apparently don't understand what happiness is. Plus, you can't "make" her happy. Here is what you can do -- do loving and caring things for her, ask her what she wants and needs from you as a partner and LISTEN to what she says, then DO them. Most of what she will tell you will have nothing to do with sex. For women, romance and love begin in their minds. That's where you want to romantically and positively influence her, in her brain.