Not strictly on topic, but sort of relevant...
Don't get any water in the fuel. Investigated an Alouette accident in Romania many years ago where the helicopter was parked on a nose down slope of about 5-6°. Fuel sample taken in the morning showed no water, but failed to consider that the drain wasn't at the bottom anymore with the pitch attitude.
Helicopter lifted off (nose down with 7 people on board, very forward CG), accelerated (nose down), climbed (nose down) cruised (nose down) and then when they started to descend and decelerate (nose up), the water moved to the back of the tank where the fuel intake to the engine was, and poof - out went the fire.
Estimated it took less than a half cup of water to put out the fire. And the fixed shaft engine didn't have an automatic relight and would have taken several thousand feet to get started normally.