These are strictly the thoughts from a amateur trying to learn a little more about rubs, but if I were to apply the same technique as I do when trying new sausage recipes I would start out with the following 3 step or catagory process:
Catagory 1:
Salt and sugar seem to be the base for just about any rub, sauce, brine etc. So I might throw in 1 TBS of kosher or sea salt and 1 TBS of turbinado or brown sugar.
Catagory 2:
Next would come the spices that most of us use darn near everyday, whether we know it or not. I would start out with 1 tsp. each of these. Since it sounds like we are looking for a course rub I would buy seeds so they could be cracked in the pepper mill to the desired consistancy. These would be ingredients like black pepper corns, white pepper corns, coriander, & mustard seed. This catagory would also include the granulated garlic and dehydrated mince onion.
Catagory 3:
Lastly. The exotic herbs to give it that individule taste. Your rosemary, majoram, basil, tarregon, thyme, and oregano. Grated lemon peel, grated orange peel, & coconut are included here as well. With these I would start out with 1/2 tsp of ea.
By the way, I'm not suggesting we have to use everything mentioned or can't use something not listed.
The theory behind this is once you have added your ingredients from cat. 2 to cat. 1 you can decide if its too strong and more salt and sugar need added. Or visa versa. Then by adding the small amounts (unless your alergic to it a 1/2 tsp of anything shouldn't ruin your day.) of ingredients from cat. 3 you can continue to tweek it until you have the right amount.
Just my thoughts because I'm too cheap to be wasting spices that cost $4.00 a bottle or more. Isn't it funny how they just keep getting more expensive from cat. 1 thru cat. 3?
Sorry for rambling.