As Shawn says, the only way to sort this out for yourself is practice - all the maths in the world won't save you when the donk stops if you don't have an idea about what picture you are looking for out of the front window.
From about 2000' into wind, note a marker on the ground (fence, road, field boundary etc) and do your normal entry to auto as you get overhead the marker.
Once established in auto at the normal speed, look for a feature on the ground ahead that is staying in the same place in the windscreen (like a collision course with a constant relative bearing) - this is the place you will hit the ground if you do nothing and is therefore an achievable landing point (you might get a bit further if you fly the EOL nicely but don't bank on it).
If you can't continue to an EOL or power recovery in the hover, note where you are at 500' and see how far you have travelled from your entry point.
Now do the same thing again but at different speeds - make sure you still do a normal entry to auto - going straight for range speed is kidding yourself that you will react quickly enough to an engine failure - chances are you will need lots of flare to recover the Nr.
If you fly this exercise accurately and repeat it on different days with different wind strengths, you will build a knowledge of the performance of your helicopter which will allow you to make a pretty good assessment of where you can go in auto.
Then, once you are confident that you know your machine, fly around and pick areas, enter auto and see if you can make them (again normal entry so you get a true picture).
Those that have been taught advanced autos and PFLs might well recognise the sortie profile. If the landing point is moving up the windscreen you are undershooting it and will land short - if it is moving down the windscreen you are overshooting it and will land long (this is better since you can always lose height but seldom gain it!).
As you increase your speed in auto, you have more energy to dissipate in the EOL and if you haven't practised one from 90 kts you will probably overshoot the intended landing area so this is another aspect to consider - once you are confident of making your intended LS (ie it is starting to move down the windscreen) then bring back the speed to normal auto where you will have done most of your EOLs from and reassess.
You really need to have all this stuff well sorted before you start worrying about reducing Nr and doing 120kt autos in 100kt winds
A good point was made earlier about using a little bit of lever in the flare of the EOL to contain the Nr and make the flare more effective - this is a particularly useful technique in helos with lively Nr as it saves winding it off the clock. I just add a squeeze (not a handful) as I start the flare and remove it once the flare effect has dissipated so as to conserve Nr for the cushioning phase.
TeT - airframe attitude isn't airspeed in many aircraft - you don't need a moveable stabiliser, it just develops more downward force as the speed increases and tries to level the fuselage - otherwise you would end up hanging forward in your straps at 100 kts.