Ability score generation below!
Method I: Roll 4d6 6 times, adding the best 3 results. Arrange as desired.
Method II: Roll 3d6 12 times, take the best 6 scores. Arrange as desired.
Method III: Roll 3d6 6 times for each ability, in order (so roll 3d6 36 times, 6 times each for STR, INT, WIS, DEX, CON & CHA in that order). Take the best roll of each of the 6 rolls.