As far as fighter combat goes, escorts should always have at
least one group flying high cover at 3,000 to 5,000 feet above
the main group, and interceptors should be set to take this high
cover into account.
As the Axis, do not overcommit to the first raid that you pick up,
because it can often be a feint. Plot your intercepts to harass a
bomber stream over the length of its route, instead of doing one
large cluster attack, which leaves you without any follow-up ability
for quite some time.
As the Allies, you should watch from which airfields enemy
interceptors are launching, then bomb and fighter-sweep those fields
the next day to pound the enemy fighters on the ground.