The type of clipart that I use is important for all of the different effects that I'm creating. It needs to be a vector drawing for sure, as non-vector drawings are bitmaps that don't resize nicely... they'll just get all bumpy and not look good. Also, I'm drawn to simply line art because if it's too complex sometimes it doesn't look as good in the different sizes. It's also good if it's a single color, usually black, because then I can change it to whatever I want quite easily just using simple graphics software. Just remember, simple is better, is cleaner, and usually creates a more sophisicated look.
So for that reason, a lot of people turn to the internet when they are searching for clipart designs to spruce up their digital creations. Sometimes you can find these easily and they're free and really well designed. But sometimes, honestly, not so much. A lot of the people who run free Xmas clipart sites have a tendency to put up a lot of ads that show up in the places where you are trying to download clipart.