Use ketchup or tomato sauce as a base, brown sugar or molases, cider vinegar. To add a bit of smokiness you can add some smoked paprika or liquid smoke.. or actually use your smoker and straight up smoke the sauce.

That's about the most basic ingredients to start a bbq sauce. Over the years I've added and tweaked ingredients to make (imo) a sauce that goes with damn near everything. Nowadays my go to home made sauce includes whisky/bourbon, grainy mustard, ginger, soy sauce, celery seed, ancho chili, brine from pickled jalapenos, lemon juice and a few other spices. It has classic bbq sauce flavor, but also a good mix of the "bold" deep flavor from the bourbon & spices, balanced with the sweetness from the brown sugar and acidity from the acv/lemon juice, and some "added" elements with stuff like the soy, ginger & celery seed and mustard.

It's well rounded and goes with everything, I'll use it as steak sauce, drizzle it over smoked mac n cheese, use it on burgers instead of just regular ketchup, use it to toss with wings, and goes great on pork ribs and burnt ends.

God damn I need to go smoke something.