My advice... make it unique and make it personal.
You have to pay close attention to things and when you find a small little thing in life that touches her, play off it. Heres an example:
When I was still dating and I started "seeing" my now girlfriend, I was not interested in getting serious (at least as far as I would tell her... but thats for another topic). Anyway, it got to the point to where she was literally begging me to be her boyfriend. One time when she asked why I didnt want to be her boyfriend I told her it was because she was like a butterfly.... Butterflies are beautiful, free-spirited creatures. To capture one is to take away its beauty. (yes, she was totally eating this up BUT it was truly from my heart)
Anyway, I finally decided to make it official and commit to her. We have now been together for about 1 year and a half and I love her to death.
So on our 1 year anniversary, I was trying to think of something special for her. I made dinner and when it was ready I had her come out and I had on Donovan Frankenreiter's
Butterfly song (an awesome song... Jack Johnson style of music) and I had gotten her this crystal butterfly thing.
So anyway, she heard the lyrics with the crystal thing and it was good
Go for something unique and something personal.