The issues are not complex. As others have said, it's tedious. You have the issue of color handled, with the original Waterford paint.

Paint chips and scratches have depth, and you want to restore the proper depth (fill the hole), and you want it to last, which involves surface preparation and treatment of any rust. Clear coat complicates the process a bit. How tedious you want to get depends on how you want it to look and how long you want it to last.

Initially, any rust has to be treated, removed, or neutralized. This is best done chemically, due to your wish not to re-paint. Let's just assume you've handled that, and move on.

Primer can be used where you're covering bare metal. Like paint, primer can be too thick, so it can be thinned and applied, just enough to cover any bare metal. Non-bare metal can probably skip the primer step. Like others, I feel a brush is often too large and applies too much substance at a time.

I like to thin the paint, and use a Q-tip or toothpick to apply it, and let it dry, use several coats to build it up. For scratches, I dab the paint on with a cloth, wiping it into scratches, then very carefully wiping off excess, It sometimes streaks, but the streaks can easily be cleaned up later.

I rarely sand the spots, but I've been known to "reduce" the touchup areas with fingernail boards or green scuffing pads and rubbing compound. Scratch-X does work better than paste wax. Too much pressure will send you right back to square one.

I've been known to abandon projects because the touchup drove me nuts.