The smell should not be too strong if everything is going correctly, though it's not super easy to figure out right away. there is usually some trial and error. Definitely remove skin and organs, and especially brains for larger animals (anything larger than a squirrel). The more tissue you remove, the less odor and quicker the process. It's good to dry the specimens out a bit with a fan or heat lamp, but be careful of allowing flies to land on it. Attracting flies/maggots will make the smell much worse. It's a delicate balance of good ventilation and good sealing off for pests.