Overpitching
In a helicopter, overpitching is where the rotor RPM are too low to maintain flight, giving the impression of "labouring". It's the nearest equivalent to stalling and is commonly caused by being overweight for the particular conditions. Reduce power to maintain RPM.

Engine Handling
One of the biggest things to unlearn when transitioning from piston to turbine is to keep your finger on the starter button once things start happening (with a piston, you tend to take your finger off straight away when the engine starts). You take your finger off when the engine becomes self-sustaining. Before then, it relies heavily on the battery or start trolley to keep it turning. It follows that, if the battery is weak to start with, the engine won't spin as fast, the airflow is reduced, the whole process becomes hotter and you could melt the back end with a hot start. You should always check the voltage available from the battery before starting a turbine engine. A hung start exists when the engine fails to accelerate to normal idle RPM. It just sits there, weakening the battery and leading to a hot start.
Pulling full power just because it's there is not always a good idea. Limitations may be there for other reasons—for example, the transmission might not be able to take that much, which is why you can’t go faster than 80 kts in a Jetranger when pulling more than 85% torque (actually, in this case, the transmission ends up in a strange attitude). Excessive use of power will therefore ruin your gearbox well before the engine (and will show up as metal particles in the oil). Many turbine failures are the result of pulling too many cycles from minimum to maximum Ng, so if you don't need 100% torque, it's best not to use it. It's also best not to reduce the collective lever of your helicopter to the bottom when descending, either, and to make power changes gently, avoiding over-and undershoots.
Maximum Continuous Power is the setting that may be used indefinitely, but any between that and maximum power (usually shown as a yellow arc on the instrument) will only be available for a set time limit.