Honestly- it takes time. I have over 500 hours and only the English and German vehicles are max spec'd. I have spec'd out all the land vehicles except the japanese landing vehicle, and haven't even touched the greyhound and puma light attack vehicles.
The reality is in Battlefield you will never be the best at everything.
How do you max out your plane- you learn its weakness's and drawbacks vs its strengths. For example corsair can have a heavier lift vs one of the zero models. So diving low in the zero and pulling out, will result in the corsair crashing- this is but one example. There are ways around this if you are the corsair pilot also.
ALSO- don't spawn camp the enemy aircraft spawn- it means the moment someone does get up and if they are half way decent- they will hunt you for the entire game in the air.
In others - it takes time and while the specialisations do have impacts- if you are getting 3 or 4 kills in a plane- you are actually going through the process EVERYONE else did.
