What is the Sunnah method of clipping/cutting the nails?

There isn’t a particular method prescribed for clipping the nails. It is therefore incorrect to regard a particular method of cutting the nails as Sunnat and strictly adhere to it.

However, Imaam Nawawi Rahimahullah has explained in the commentary of Muslim Sharif that one should commence with the index finger of the right hand, then the middle finger, followed by the ring finger and then the baby finger and finally the thumb. Then commence with the baby finger of the left hand, then the ring finger, followed by the middle finger, then the index finger and finally concluding with the thumb.