In addition to the excellent advice already given, carefully watch your meat purchases. Read all those little labels to make sure you don't have meat that's already been injected with a salt water solution. If you do buy something that has been "flavor enhanced", cut down or omit all together the salt in your rub. Those labels should carry the percent of added ingredients. The higher the percent, the lower the salt should be in your rub.
FWIW, it's getting harder and harder to find plan old unaldurated food these days. We're on a salt restricted diet. It's getting to the point that I have to read the labels on EVERYTHING. (sigh)