Your girlfriend always appreciates getting flowers and candy but everyone does that. To really set yourself apart from her other boyfriends you have to be creative. One of the best ways to do this is to put some time and effort into a special gift for her. I really impressed my girlfriend on our anniversary when I made her a blog/timeline about our relationship.
I told her how much I loved her and told her why I loved her. Then I included all places we have been together in chronological order. Including some of her favorite pictures of the two of us was a big plus. I used OurStory which is free to use. You can get really creative and the best part is you both can update it as your relationship keeps on growing. After you show her your blog/timeline, make sure to keep updating it every now and again. Your girlfriend will be impressed that you are thinking of her. My girlfriend loves the fact we can both work on it anytime and its like an online scrapbook of our relationship.