I can give you mine. I do a ratio of 50% tallow 25% beeswax 25% coconut oil.
Take the grease/tallow and render it again in a crockpot on low. You will want to do this 2 to 3 times, to really soften the tallow and completely remove debris or gristle - strain through a sieve or cheese cloth each time you render. Set aside. Don’t skip this step, even if you have rendered tallow from the store.
In a double burner melt down the tallow first. Stir often until the tallow becomes liquid. Then add beeswax - you can soften the beeswax ahead of time by putting it in a waterproof container and submerge in hot water. You’ll want to stir often and make sure everything is incorporated - beeswax can take a while to melt down.
You’ll want to add the coconut oil last - it has a low burn point and won’t take long at all to blend in. You can then use an immersion blender to really emulsify all the ingredients, but don’t do it for too long or you’ll get whipped tallow butter
It won’t hurt to buy a fragrance oil you like - it’ll take a lot to overwhelm the smell of tallow. I think honey or vanilla complement the tallow scent, but my favorite of the ones I’ve made is a cinnamon-orange. The orange fragrance didn’t really come through, but I put about 1 tbs of cinnamon into the mix and that darkened the mix some but has a great scent.
Make sure your ingredients don’t have added water. Tallow has a decent shelf-life, but additional water can make it go rancid.
BTW, I played around with that recipe above, and also tried one that has 50% tallow, 25% beeswax, and 20% castille soap shavings (I also did one that used tallow soap shavings) 5% oil of choice (I used coconut oil). I liked that one too, but it doesn’t penetrate like the first recipe does. It’s more of a finisher/ buff conditioner than a leather reviver.