Love in a bottle
While the words you write are the most important thing, presentation can make it even better. Timeless Message can help you with the presentation part, or you can go to a craft store and buy a nice bottle, a couple sheets of special paper, and a bit of ribbon to do it yourself for a lot less. (Thanks to whoever pointed me to Timeless Message a while back – I thought it was on the comments here but I cannot find it.)
As to the words, give it a lot of time and effort. Write and rewrite, do not just bang something out Christmas Eve. You are trying to put your heart on paper here!