One could try the Towering Takeoff Method used on the Bristol Sycamore; notorious for lack of power and manoeuvrability.
On the ground accelerate the rotor to max permissible. IIRC 287 Rrpm.
Pull the collective up at the same time opening the throttle to keep as the power at max whilst you overpitch to min Rrpm.
Pitch forward with the cyclic at the same time milking the collective to maintain Rrpm as you transition forward and down.
When you achieve level flight continue take off as normal.
Worked every time.
Still used in a way. On the S76A+ we would use a similar technique so that one could throw it over the side of a platform and allow gravity to achieve VTOSS.