Shifting is much more of an art than a science. Experiment with it, practice it. Find how it works best, and become a master.

 

When upshifting, zero throttle input is required to rev match. You only need to be on the throttle when the clutch starts to grab so you can smoothly transition into the next gear and continue accelerating.

Obviously the engine will decelerate with the clutch pedal in and no throttle input...