Well, to start you off, you first need to understand that the USMC based at Wake island on 21 Dec. 41, lost alot of aircraft due to mechanical failures or shot up before the game action starts you off as, you, the pilot, are starting the missions after being kicked in the butt. The history is pretty close as to the game anyway for US forces. most of the time, they were lucky to get 4 into the air and have 4 come home without any problems. They were cut off from US resupply routes so, again, they went with what they had in store for them.
As for the Japaneese, well, they had a good number of aircraft used for Wake Island missions. but you wont see the accurate number in your game.
Once you get past 3 missions in campaign, your notice that you'll have to fly and fight like no other, because there are a couple of missions that have like 25-50 planes to your 4 to 6 wildcats... while your still on the ground trying to take off to get into the fight.
But practice will make perfect. first, you want to know your plane. do some take offs and landings without any enemy forces around, then go up against 1 plane at rookie level. and keep working the levels until you beat an ace on your own. Then you should be ready for a 1 against 4 odds combat
remember that the AI in game are not all that smart, especially your wingman or C/O
but dont you worry there mate, you will work up enough skill credit to be your own C/O and you have to babysit your wingman. Because he will get picked off pretty quickly.... unless your flying online, then it's up to your real life wingmans skills.
If at first you dont succeed, try it again
Other missions are easier or harder than what you have already flown. Hope this helps out. Happy flying there mate
good luck!
Riken