What he said.^^^
Your goal is to prevent feathers breaking and freezer burn.
1. Wipe off any excess blood. If it's in the down feathers the taxidermist can take care of it.
2. Tuck the head or at least bend it back next to the body
3. wrap in panty hose or plastic (this protects the feathers)
4. Put it in a 'Freezer bag' ziplock or two (protects from freezer burn
5. I've also heard wrapping the feet in wet paper towel before freezing helps lock in some moisture and prevent freezer burn but don't hold me to that one.
Then God said, "Let us make man in our image, in our likeness, and let them rule over the fish of the sea and the birds of the air, over the livestock, over all the earth, and over all the creatures that move along the ground."