Pick one type of gunset (don't flip between planes with different guns), go offline, set the ammomultiplier really high and shoot at the drones at strange angles. Don't try tail chases. Shoot off several 1000 rounds and get some kills. Try and make engagement ranges typical of what you are used to seeing (ie, if you tend to take long shots, then practice at some distance, if you are used to taking point blank shots then go for those).
I usually take something like the P51 when I do this since I know the .50's practice will also help me with just about every other bird that packs .50's (P38, P47, P51, F6F, etc).
-Soda