For me, I usually find some swarm calls in a hive. I find the queen (mark them whenever you find them) and remove her. I leave at least two queen cells in there. I then remove the other frames that have queen cells and put them in nucs. I put a minimum of 2 queen cells per nuc and add another frame of eggs, larva, and nurse bees. I then sometimes shake a fame or two of bees in the nuc as well (the cooler the weather the more bees I put in there). Put some syrup on them and walk away. I'll check them in a week or so (depending on the age of the queen cell) to make sure the queen emerged. If she has leave her alone for another coupel of weeks before checking her laying pattern. If the pattern looks good mark her and make note of her age and let the hive do it's thing.
Once the nuc is formed I will also use them as breeding nucs for grafted queens I make from my better queens. I really like having back up queens and frames of brood, pollen, and honey for any needs I may have as a beekeeper. An established nuc is also a great place to put a purchased queen so you can review her work before proceeding. I've also found purchased queens are better accepted in nucs than double deeps.