I have not given any measurements as it is all to taste and the amount you make. This is a family regular and my personal all time favorite potato salad. It is easy and can be adapted and will always taste good.
Cook the potatoes, skin and all, in a large pot of salted water. Slowly simmer the potatoes till cooked. Now here you have a choice to either leave the skin on the potatoes or peel them. Cut the potatoes into largish chunks and set aside whilst you make the dressing.
Mix equal amounts of a good mayonnaise and sour cream with the finely chopped onion, chives/parsley, pepper and if you are adding any of the other options.
Pour over the still hot potato and stir gently. Potatoes need to be hot so they soak in some of the dressing. Scatter chopped up hard boiled eggs over the top and gently mix again. Keep in fridge till cold. I like to make this the day before I am serving it as some times it needs more dressing once it has cooled.