This is more than 5....sorry :).
---Care for her. In actions as well as words. Inquire about her health, her family, ask her how things are going in her life or if anything is bothering her, let her know you are there for her, contribute your opinions to her doubts and questions without forcing anything on her...etc.
---Give her, her space, and privacy at the same time. If unsure, ask her. Don't question her too much. Let the small stuff go.
---Show her Trust. Show her you can be trusted too, by being dependable and honest.
---Give her reassurance and some heart-to-heart communication when she is upset. Never ignore or mock at her tears. Hug her when she is upset. You don't even have to say anything sometimes.
---Be affectionate. Just a protective arm around her, would make her feel good.
---Compliment her often.
---Respect her as a individual with her own thoughts and ways of doing things.
---Appreciate her efforts. Try not to take it for granted...
---Be an equal contributor at home and elsewhere. I had a BF who would do the dishes, ask if he could help me cook, or keep the garbage out etc. without being asked to do so. It was very touching. He wouldn't even start eating until I was ready to, sometimes. On his way to the kitchen he'd take my plate too. It was these little things that touched me.
---Be attentive to her. A good listener..
---Be spontaneous and fun-loving. Keep things interesting. Tease her.
---Above all, do be yourself. Be your own individual. Have your own interests in life. A girl does appreciate that.
No one is perfect....but it helps to keep these in mind. Thanks for asking that question! It already shows you care about your relationship.