Listen to her. Practice hearing what she says, and practice remaining silent until she has finished having her say. There is no substitute for face-to-face communication.
Tell her how much you admire her. A bouquet of flowers or other gift is always welcome, but you don't have to spend money to let a woman know that you cherish her. Simply tell her. This will help you to keep from taking your relationship for granted.
Be accommodating. If a man cherishes a woman, he will be willing to rearrange his schedule when possible or take on an extra chore or two. If you are always inflexible, that will communicate the message that you are not putting her first.
Respect her. Don't belittle or dismiss a woman's feelings or points of view. Part of respecting a woman you cherish is recognizing that her feelings are valid, even if you don't agree with them.
Pay attention to how she cherishes you, and reciprocate that. If the woman in your life likes to leave you little notes, or do you favors, there's a good chance that she will enjoy the same things in return.