I have very fickle eyes and need my visuals to be tack sharp, so I have been using Reshade to improve image quality in Aerofly FS2. It's only available on Nvidia GPUs. This tool is a kind of injector which allows you to add a variety of different shaders to add visual effects, such as sharpening, colour changes, HDR, etc.
I have attached some "before and after" images showing a crop from my screen before (no reshade active) and after (reshade activated with a variety of shaders). I am running the sim at max settings, 2560 x 1440.
Reshade can be found here: Reshade.