Occasionally, do something for her which you personally may not like

At times just do something which she likes which you may not have a preference for. For example, if she feels like watching a chick flick you could take her out and watch it with her even if it bores the hell out of you. She will know that you are doing this only for her.

Remember the word occasionally. You don't have to do anything which you don't feel like doing just to please her, that would be a bit on the servile side. Girls do like men who are decisive and are usually quite happy to just go along.