This is a great question, one I’m sure we’ll revisit in the future.
The first thing that comes to mind is salt. From what I’ve seen and tasted, home cooks just don’t use enough of it. When I see home cooks reach for it, they pinch tiny amounts like it’s poison or worse, shake salt shakers vigorously. (and I’m still not sure anything comes out).
Salt is immensely important in cooking. It enhances flavor and in many instances, it changes how food cooks. It’s the only rock we eat directly. And of the four tastes our tongues can perceive, (sweet, sour, bitter, salty) salt is the only thing that produces . . . well . . . salty.
Of all the choices on the shelf, kosher salt is my go to. Its crystals are larger than table salt and so, make for easier pinching. I don’t use a shaker and definitely not a salt grinder. Grinders are great for volatile spices like black pepper whose flavor dissipates minutes after grinding, but for a mineral (salt) fresh grinding doesn’t make a bit of difference.
For adding it directly to food I always have a small bowl in the kitchen. I take a small bit between my middle and index fingers and my thumb, and rubbing them together, dust its magic. Four to six inches above its destination is best. Too close, and you risk uneven distribution, detrimental to slim items like fish filets. Too far and you loose control of where it falls, never a good thing.
Now be liberal with the stuff, but not too liberal. You can always add a little at the end. Just keep in mind the surface to mass ratio. For that fish filet, not too much, but for a big fat steak you’ll need a little more.
To cook with salt, it takes even more. When boiling water for pasta or blanching go salty, about one tablespoon per quart. For vegetables, in addition to making them taste better, it helps them retain color. For pasta, the water is the only chance you get to season the pasta itself.
The implied principle, and the real answer to this question, is this. All aspects of a dish or meal need to be seasoned properly from the start. If you forget to salt your pasta water, you can’t really compensate by adding more salt to your sauce. While it seems like it should balance itself out, you still end up with salty sauce over bland pasta. . . . not so good. Restaurant cooks have a firm grasp on this concept, and I think it is one of the reasons restaurant food tends to stand out over the average home cook’s.