You're overthinking this. Skin the potatoes, cut them up, boil the s*** out of them. Drain the water, return to heat for a minute or two, start mashing them. Add butter and milk - keep heat on them. Keep mashing them every so often, while reducing them down to the consistency that you want. If you take it down too far, add some more milk, and try again.
Rocket science, this ain't.
best MP are 1/2 potatoes and 1/2 heavy cream..reduced
and truffle salt.