Get her a card.
Even if you cover all your bases, and get her something naughty and nice, you'll still come up short if you show up without a card. Skip those long cards that have ten paragraphs of pre-written sentiment. Opt for a cute, sweet card and write some thoughts of your own.
It may be Christmas, but when it comes to cards, think Thanksgiving. Look back on the year that's gone by. What has she made you thankful for? Write a few of those things down and she'll be putty in your hands. No corny poetry required.