how to trim properly

[MD_Zebo]

I've read spitfires came pre-trimmed as far as roll and elevator go, they were all test flown and if they rolled one way, they would bend the ailerons correspondingly with a tool abit like a tuning fork, them there were re tested and only when the tester ( I can't rember his name or which book I read these facts in) would release the plane for service.
Alot of BOB pilots used a touch of rudder trim either way so they didn't fly straight and were therefor harder to shoot down.
you can always center your bubble when shooting.

[MD_Zebo]

It was Alex Henshaw, cheif test pilot and Castle Bromley, the book was SPITFIRE, a complte fighting history, and yes, I have read it all!
They also trimmed elevator in the same manner.
So your spit SHOULD be trimmed, as for the yellow nose basterds, well, they're for shooting at, not flying

[K_Freddie]

You winding yourself up too much...
Just trim for maximum speed (at current throttle, ect).. this is the simplest and best indicator of correct trim.