tl;dw set a custom game 6x6 with 34 mines, leaving only 2 spots mine-free. Your first click will always be safe, so as soon as you find the other spot, all remaining mines will be flagged automatically. From each corner of the field, click the square diagonally toward the center from it so it will reveal the 8 squares surrounding it even if it's a mine, winning the map in at most 4 clicks. If you run out of lives, just restart and continue. Good method!