Get the whole heli vibe free with no blades on first by balancing the flybar paddles and tail blades using tape with some trial and error (feel if the vibe gets worse or better)
Don't go over half throttle with no blades on. Add a drop of glue to the flybar when you put the paddles on, so you can be sure they won't fly off and smack you one.
Add the tape along the length of the blade. Start from the tip and work your way in. Do it on the bottom on the blade to keep the top of the blades clean looking. If you add tape to one blade, and the vibrations start to go away, add more till totally gone. IF the vibe gets worse, pull the tape off that blade, and apply new tape to the opposite blade.
You should be able to really fine tune the balance using strips of tape.
Start with a 4" piece and see which blade to put it on to help reduce the vibe. Keep adding more (or removing tape) to fine tune it from there.
Shouldn't take you more than 10 minutes to complete the whole "balance proceadure"
And it definatley improves how the heli flies, as well as how the gyro operates.
OTherwise, you will need a balancing system to know exactly which blade it is. You can mark the blade grip with a star to know which blade will take the tape in the future too.
Once you are used to doing this, you can do it in 5 minutes flat after a rebuild.