I have never mixed MM Acryl to achieive a different shade for airbrushing. Is there any trick to mixing? Other than what is obvious, like ratios and such. Should I mix in my airbrush paint cup or seperate bottle? How long can I keep my mixed paint?

Any help is appreciated.....Hey look! Ive been promoted to Major!, must have hit that magic post number....

I tend to keep xtra bottles for the purpose. And if sealed they should last.

I use fil containers to keep my mixes. Back before our photo department was all digital it was real easy to find them, not it's a lot tougher....