My husband and I have done our own processing for about 3 yrs now and we add beef suet (beef fat )that can be purchased at your local grocery store for next to nothing or sometimes if you ask the butcher they give it away and that is always wonderful! We also use pork loin. It is more expensive but it doesn't take much. The pork loin that we don't use we cut up for boneless pork chops. You only need t use about 3 or 4 pieces of beef suet or pork loin for every handful of venison. You can also use seasoning salt and try adding other seasoning to suit your taste. We do use a seasoning in ours but a friend of ours makes it himself and I have no idea what he puts in it, he always says it is a family secret!
Also the more of the muscle you cut out the more tender your meat is. We have also found out that the backstraps of the deer are very good for butterflying and make the best little steaks. I cook them with some sauted onions and mushrooms and garlic and the kids go nuts over them! Talk about getting them to eat, no problem there! Anyways, I hope this helps! Good luck!