treat her the way you treat your regular friends, except in a somewhat more sexual way. Don't do whatever she says just because she says it. Don't respect her more than you respect yourself. Feel free to disagree with her at times and stand your ground. If she does something disrespectful, feel free to get mad and/or call her out on it. Don't be such a boring, nice guy.
Also, pursue action dates and pursue action in life in general. Don't be a boring person, especially when you're around her.
And why would you wait 3 years before asking a girl to marry you? Going that long is just asking for trouble, imo.