RE: Blade CX2CX2.
Put on the training balls until you're confident enough to raise it without it tilting and hitting the blades.
When there's an imminent blade strike ... CUT THE POWER immediately!
Driving the blades into something hard breaks more of them then letting them hit without the motor pushing on them.
It also saves the 4-in-1s, to pull off the power as soon as something bad is going to occur.