Here's my take on rubs. I looked at several rubs this morning while in Walmart. Most of the rubs have salt as the first ingredient so they have more salt than any other item. Another rub had sugar as the first ingredient and turbinado sugar as the second ingredient with salt as the third ingredient.
Salt is not a tenderizer as someone else stated. It is a preservative. It is also an acquired taste and that's why we end up eating a preservative. The less you use salt the more you come to dislike it when the foods have a little more than you're used to. Perhaps your body it telling you that salt is bad for you. Use it if you must but commercial rubs have way too much of it. I tend to use a little salt but for me a little goes a long way. Other members of my family are used to more salt than I am so things don't taste right to them without it.
Sugar seems to be used as a filler in the jars of commercial rubs. It will caramelize and then burn so you risk ruining your food. That's why so many BBQ sauces are only used at the end of the cook. Some people like meat to taste like candy. So be it.
Look at some rubs in the store and some rub recipes online. Develop a skeleton recipe or multiple skeleton recipes; one for beef, one for pork, and one for chicken.
Say you have your skeleton recipe for chicken rub but that day you feel like adding something like lemon pepper. Go for it!
Many rubs really need at most only 4 or 5 ingredients to develop a skeleton recipe. A lot of them use onion powder, garlic powder, fresh ground peppercorns, salt, and maybe sugar. Chipotle powder or cayenne powder can be added if that suits your tastes. But remember, some people absolutely swear by using only salt and pepper. Start out simple.
Keep notes and play with the recipes. When you get bored with any of them, and you will, then change it. Have fun!
