But what if you are going into a clearing? Or don't get that much practice? The above method is fine, but you need to be doing it a lot to get it right every time. One way that will cover both the above situations is to start the flare very much earlier, so that you are virtually stopped quite high up. Then carry on as if you had an engine failure in a high hover, that is, dump the pole to get going vertically downwards and haul it all in at the end. In a vertical autorotation, there is a phenomenon known as dynamic stall that will help, where an aerofoil that is rapidly stalled can produce double the normal lift, just for a moment, because the breakup of the boundary layer on top is delayed for a while, if indeed you don’t actually create a little vortex along it that improves lift even further. Do not try to gain speed, as you will split the lift vector and increase your rate of descent.
If you're likely to be ending up in trees, as you might if you have the choice between them or power lines, aim between two tops, tail first or low, or at least moving gently backwards. The worst thing to do is go in nose first, because the engine and gearbox will hit the ground before you do. The height of the tree is less important than the height at which the branches start, and if you are over them regularly, you might like to carry a good length of rope to help yourself get down. Having said that, it will be easier for the SAR guys to pick you up from the top. With short trees, denser areas provide the most shock absorbency
– don't worry about branches overlapping, as long as the trunks are far enough to allow the fuselage to settle and the main rotors to miss them (actually, the main rotors can be used as an umbrella to reduce descent). Fewer trees in an area actually become obstacles. Dead ones provide no absorbency at all. Pull the collective when you are in the trees.
If the surface is sloping, try to land nose up. If you flare a little, you will increase your chances of getting it right first time as the attitude of the skids will match the slope of the ground better.
Whereas an aeroplane is better suited to protecting the occupants from forward impact, the helicopter is better suited to vertical motion, so forward movement should be reduced as much as possible, especially over hostile ground – the cabin can be distorted badly just from the couple between its forward motion against the drag from the skids on the ground. As it happens, a zero speed touchdown at 1500 feet per minute on soft terrain would probably not result in many injuries.