My recipe seems to wander around a bit, but it always includes onion and garlic powders, black pepper, either red pepper or some hot sauce, worcestershire sauce, and soy or terriyaki sauce. If I use soy, I also use some brown sugar. I don't like it too sweet, but just enough to balance the salt. I use about 1/2 tsp salt per pound, the rest coming from the soy or terriyaki. Lately I've also thrown in some ground ginger. All the amounts are fairly flexible, maybe 1-2 tsp of each of the dry ingredients/pound except for the hot stuff which is to individual taste. I find that if I use just enough soy or terriyaki to fully moisten the meat without making a puddle, it seems to come out about right. This means that the spices don't end up in extra marinade that you throw away when you take the meat out. I put it in a baggie or some sealable bowl and let it sit in the frig overnight. I usually shake it up whenever I happen to be in the frig for a beer or something. Lots of opportunities for shaking.
If you partially freeze the meat before slicing it is easier to get good uniform slices, though the weird shaped pieces let you know it's real jerky! Of course it also helps if the meat is of uniform shape, but that doesn't happen often. The best I have had was the above mentioned brisket, which was on sale, but was very lean and didn't even have much of the internal fat layer you often get in brisket. However, like I said, if you look at the price per pound of jerky, you can afford a pretty nice cut of beef to use to make your own.
Chuck