Hmm. Anything more specific you need to know?
You can buy leather needles at Joannes, they have sharpened tips to slice through the leather. You shouldn't need them for fox fur since the leather is so thin, but they're good to have on hand.
Other than that, always make your cuts on the leather side with a razor, never use scissors or you'll trim the fur.
If you got a fox face and want to keep the ears, try the keywords 'rehydrating fox face', that out to give some useful results with pictures and descriptions.