Activate Force Speed (works best with grade 3 speed) and slash once at their front to lure them down. Then, run around behind them and slash their back as many times as possible. This works best if you push them in a corner and complete the procedure.
Use the following trick to kill Reborns, Reborn Masters, Jedi, and other Force users. Use Force Grip to hold them in the air, then throw your lightsaber at them to kill them. It is harder to do to some, but if you timed correctly you will hit them. This usually works best with Grip level 3 and Saber Throw level 3, but is still possible to do with the other levels.
When fighting the Reborns at the start of Chandrilla (after the bridge is blown up), lure them all to the bridge then jump over to the other side. Two of the Reborns will attempt to jump over as well, but will fall to their doom.