If you have Ravelry and an updated queue, that's perfect. Otherwise, comb through your books, your magazines, online patterns, your sketchbooks...whatever. Make a big list and aim for variety. Sort it if it makes you feel better. Consider gifts you want to make. And so on and so forth.
This is pretty straightforward but may take a while. In my case, I have my Ravelry queue plus a huge number of sketchbooks/loose pieces of paper with ideas on them/etc.
(Also, for Christmas, may I suggest Buying Handmade?)