It depends on what I have on hand, and what we feel like.
Hard shells. Taco boats. Flour or corn soft tortillas
Cumin and ancho chile powder (or chipotle powder), some salt on the meat.
Beef, chicken. Sometimes fish or just vegetarian.
Sometimes black beans, sometimes refried.
Sauteed peppers and onions (just until slightly softened, I like 'em crisp; use oregano and salt here)
cheese (shredded cheddar type or queso fresco); sour cream
Lettuce, tomato, green onion or thin sliced sweet or red onion (I don't use yellows at all); cilantro
Jarred salsa (we like Frontega brand) or homemade fresh (red onion, tomato, jalapeno, cilantro, lime juice)
For a more "authentic" taco, we do thin corn tortillas, doubled; chicken sauteed with cumin, chile powder, salt and lime juice; fresh salsa; cilantro, and more diced onion.