I'm sure there's some pre-flight performance stuff they taught me,
You don't need much - the OGE hover ceiling vs gross weight chart in the POH is the place to start having worked out your pressure altitude and expected gross weight.
You need at least OGE performance and ideally some extra - unfortunately there are no graphs to tell you how much extra you have got.
Hot and High is correct that the MTOW isn't a power limit but taking 5 or 10% off the weight would guarantee you a thrust margin of probably more than you need if the weight line is the first limit you hit rather than the OAT or Pressure altitude.
If you have the performance on the chart then you just need to confirm it before committing to landing - I'm sure you check your hover MAP against the placard to make sure it is correct before transitioning.
Once in the vicinity of the landing area, pull to your calculated max take off MAP - ie your max continuous plus 2.8 to make sure it is available without Nr decay or exceeding any other limits.
One problem is that the OGE graph is based on 5 min take off power and not the max continuous MAP which may pass people by if they are not paying attention - the problem being that if you need 5 min power to achieve OGE, you have no spare to deal with turbulence or any unexpected rate of descent - hence my advice - especially if you are hot and high, to have a thrust margin.
Now a 5% thrust margin was defined in various military Operating Data Manuals (same as POH) as sufficient to overcome light turbulence or manoeuvre gently in the hover - in a couple it quantified a vertical rate of climb of between 100 and 200 ft/min so it is not a huge amount of excess power.
Clearly such advice doesn't exist in the POH but you could experiment to see what difference 1 inch extra MAP gives you from an OGE hover - it will at least give you an idea of the difference between Sea Level at plus 23 degrees and 5300' at plus 23 degrees since the max continuous MAPS are only about 1.4 ins apart from the placard.