As the first addition to the Hogsmeade Christmas Village, I converted some Halloween Owls I got on sale into wintry Harry Potter owls. It was actually a bit easier than expected; I used a dremel drill to remove the 'Halloween' aspects of the models, then simple acrylic craft paints to repaint them.
The owls, as seen above, had a few items that needed to be removed in order to convert them to Wintry Wonder. I dremeled off the spiders, rats, halloween mask, and the high collar of the dracula cape. I didn't dare remove the entire witch hat or cape, as it would have required sculpting a large piece of the owl. I used light strokes with the drill to make new 'feather' imprints below the areas where I removed things.
|The original owls before the dremeling
|Owls after dremeling
From here I began doing layers of dry brushing and washes.
Washing is taking a darker color paint and diluting it with water. Take this and paint your item, allowing the watery paint to seep down into the crevices of the item. This will help accent shadows. Generally I use black paint for washes, but occasionally other dark colors if it will fit in better.
|A very light Black wash in Hedwig's wings
(For the eyes, I did golden yellow, then very tiny black dots on top for pupils. It was surprisingly difficult to get the pupils to face the same direction!)
Dry brushing is when you use a lighter color paint, put a small bit on a brush, then remove most of it on a piece of newspaper or paper towel. Then very lightly paint with the brush so that only the top bits of the surface (the highlights) receive paint. Typically I do a wash first, then a dry brush once it has dried. If you do a wash over a dry brush it will darken the highlights a bit.
|Brown owl with lighter brown dry brush on the feather edges
For Hedwig, I needed to convert the witch hat into either something Christmasy or Harry Potter-y. I decided to paint her wearing the Sorting Hat. The hat was light brown, and I added eyes and a mouth with a darker brown paint. I then did a dark brown wash to give it better depth and texture.