trial and error is what most guys do.

start very rich and gradually lean it out to the correct mixture with each flight.

There are some guys, including myself, that hold the heli by the skids above my head (like a hat) and have another trusted experienced collegue to dial the mixture in until it peaks and then back off 2-5 clicks. Perfect!

This is INCREDIBLY dangerous for anyone with no idea or experience in helicopters as you are effectively holding a gyro on top of you.

I do not reccomend it for anyone in the beginners forum to even think about!!!