OK, seriuos answer.
I'm no ace at this, but have learned lots especially in the last few months. Here's what's worked for me.
First, change your default view so that you're looking "over" the top of th Ostwind's sight. The sight block is too low to see the target's path off center, so deflection shots are near impossible. Then, change your default side views so you ALWAYS see over the top of the armor shell.
Leave tracers on in osty, at least until you'r a Master Gunner. It makes learning possible, and it tempts fighters to strafe you -- for MUCH easier gunnery solution for YOU. In field gun, the choice is tougher, becuase they're so darn esy to kill. I tend to hold fire longer, and pretend the gun's already down, until they've given me my preferred shot -- and tracers off can help that impression.
At ranges under 1k, the osty gun is pretty much flat trajectory. The trick is to lead the target. Diving planes will be LOWER than current image when the round reaches them, so when they're coming straight at you shoot jsut below the plane image. When they pull up, duh, shoot just above. Dont bother trying at ranges over 1.5 -- the system updates visual positions more slowly farther out than that, adn likely you're not seeing the target's real position on your screen.
For side tracking shots, it comes down to visualizing their flight path and hosing the tracers out. Sometimes you'll get the lead jsut right, and the shot fails becisue of the slow rate of fire -- but it evens out in the end. Keep scanning all directions for enemies coming within the 1.5 tartget ranges, and dont forget straight up -- easy to do since only a few attackers will take the time for the high percentage but time consuming high angle attack.
In osty, park on concrete so you can "land" even if you lose a track. Also prevents a "Ditch" of a damaged tank geting counted as a death. If you dont plan on moving, turn engine off and listen for the attacker's engines -- you can turn outside volumes up and inside engine volumes down too. Some drivers will listen for the whistle of a bomb oin target, and might even "land' by typing /.ef at the last moment -- i mention this because its done, not as an endorsement of what some might consider unsportsmanlike conduct.
In the end, though, "sportsmanship" is what you consider fair and fun in THE GAME -- dont let anybody tell you what you "shouldnt" do. Fly the plane or vehicle you want, the way you want, until the other guy pays your bill.