From: Chicago, Illinois
LIquid Sky has some good advice on extending the LW. Basically, you want to manage it so all new pilots are fighter pilots.
As Germany, you have to make liberal use of the Disband feature for air units. There is no point to keeping lots of depleted units you don't have pilots for. I have found training pilots to be about worthless; it causes big ops losses, and uses alot of fuel, so it's pretty useless. You have to just live on the meager replacements, and reinforcements. You can make an argument that putting bombers up with rookies is a "why not" move, since you may have bombers in the pool, but if your opponent is bombing fuel I think you're better off just not bothering.....waste of fuel.
The most important are the day fighters. You can extend their life first by funneling replacements there, then disbanding night squadrons and usings those pilots in day units. I disband all the HQ units fairly early, just to reduce clutter. I keep a couple FB HQs, only so they can convert to a new type before it's available
The FW 190 is quite good, the Bf-109 is serviceable. The Bf-110 is dead meat against any Allied fighter, and should be sent to Romania and retired fast. The Me-262 is AWESOME, the other jets are useless, particularly the Me-163...that's my experience.
Ultimately it's a losing effort no matter what, but if you can keep the LW in the air until the end it makes a difference