Pick a range then get stronger at it. 3x3, 4x6, 10x2, 5x5... consistency over time.
when you've milked a rep range and have hit a hard wall, reset and progress with a different range for different emphasis.
As a general rule, training heavy with a total of 5-25 working sets will be good for strength and training moderately with more than 25 working sets will favor size/endurance.
"You must have a very strong reason for doing an exercise. If you don't, scrap it and move on." -Jim Wendler