The dot method. You don't want a lot, just filling in microscopic flaws between the metals of the IHS and heat sink or water block. It's just to transfer the heat since air is more of a thermal insulator.
Honestly theres only one best way.....put a medium sized dot in the centre. Others can say an 'x' or a box.....50% of the thermal paste is wasted if u try to act cool like this cuz it gets on the sides.