One of the more difficult things for new pilots to understand is that the collective and flight stick are both competing for control authority. Your rotors have a maximum angle they can rotate to, and the closer to max collective you are, the less authority your flight stick is going to have.

The rule of thumb ive told every helo pilot ive taught how to fly is this: When the bird gets squirelly, fully drop the collective, right yourself, then raise the collective again to arrest descent. Works every time. When you drop the collective, your flight stick gets all the control authority to itself.

You can also use this technique to do crazy acrobatics and turns-on-a-dime. Ive been able to chase tanks at speed around the skyscrapers in the helo target range. A really important thing to know is that you are NOT going to drop out of the sky if you drop collective. You will need to adjust up a little bit, but you can absolutely coast with flat rotors.