Add chopped potatoes to well-salted cold water, then boil until tender, about 10 minutes. Keep an eye on them, because there's a fine line between undercooked and overcooked. I hate them undercooked, and the only way I can tell is to taste a piece. It needs to be soft and tender, maybe with the teeny tiniest bite at the middle (it will continue to cook when drained), but not falling apart and mushy.
Drain potatoes and allow to cool to room temperature, before carefully spooning through mayonnaise one spoon at a time, herbs, and season well with salt and pepper. You will see when it's dressed to your liking. If you don't allow them to cool, the potatoes will soak up the mayo and become mushy.
Add one or more optional extras if using.