Placing the slices firmly in a toaster, or on a fork, or evenly on a rack when toasting by gas.
Keeping the toast at a distance from the source of heat that insures a steady but not too rapid change.
Turning the toaster or the slices to cook each surface in turn and thus to make the process slower.
Stopping the process before carbon is formed and the toast "burned." (A good technique does not include scraping the toast!)
The aesthetic element in toast-making might be a pretty shape of the slices, say triangular pieces, and a dainty arrangement. In this case and in others it is true that the result of a good technique is aesthetic, in that correct manipulation while securing the desired chemical change also develops the pleasing golden brown that makes the toast so attractive.