I was just re-watching a you tube video by Brent Walton of QN4U where he was going through his basic rub. I remember it as being a pretty good rub. I think Bent also thought it was a pretty good rub, but maybe he will post later.
Brent had several things that he added to his rub but said if all you had was salt and pepper, that would be a good rub. His proportions were: 1 Tbs. salt, 1 Tbs. pepper, and 1 Tbs. garlic (he then also added onion powder, a bit of cayenne, chili powder, paprika, and brown sugar). I have no clue whether that is a typical ratio or not.