1) The choice of the ingredients. Healthy, fresh and of selected provenance. They represent the most important part.
2) The cooking temperature must always be medium/low or low. Food must be respected, not violated by the heat, that way it is not damaged and it maintains its taste and organoleptic qualities.
3) Be careful with sauces and onions and herbs lightly fried in oil: never leave them on the fire, they may turn sour and acid. Use a pinch of sugar also in the sauce to avoid the acid effect.