Once you've lost your tail rotor and are spinning, simply gain altitude. You want probably 150 meters or so for this to be the safest. Note that as you're gaining altitude, your spin is faster than before – this is because of the increased torque from the main rotor.
Once you're at about 150 meters or so, do full down collective. Your spinning will stop. Point your nose in the direction you want to go and dive towards it to gain speed.
That's it.
It's really simple.
From there, just do a normal landing procedure as noted in the 'Agility & Landing' chapter. Oh, and don't be too concerned if you hear a horrific screeching crash sound upon touching down – that's Arma 3's way of saying you're alive. Unless it's followed by an explosion. Less alive in that case.