Hi there,
when you try inverted for real:
check your fuel clunk....that it moves around freely so your fuel supply is good
check your idle up setting...that the throttle arm moves as it should...'V' curve
check that all is nice and secure on the heli.
Keep nice and high before pulling back on the cyclic.....you will find the heli is quite wobbly as its weight is above the rotors.....gentle inputs will see that everything is ok.
If the engine starts to 'bog' then pull out straight away....unless you are good at autos
In fact.....I would try doing simulated 'failures' on your sim....try autos inverted before flipping the heli the right way up and then landing.
Inverted flight is cool....your heart will race I can tell you

its a pure 'rush'
you will find the heli can loop within its own length.....rolls are pretty cool as well.
Just take things easy....if the heli seems to 'bog' you might need to alter the pitch curve etc.....keep nice and high and talk yourself through.....and dont forget which idle up mode you are in......as you land just be sure to check your switches ......drop the collective GENTLY otherwise if you are in inverted mode you could drive the heli into the ground.....in all the excitment its easy to forget simple things.
Inverted flight is a big step....but pushing our limits and adding to our experience is what its all about....good luck....and make sure you post here and tell us all about it.....

Awsome
Rob
PS what pitch setup do you have? I can point out a great link about this if you like.