When I find my piloting skills starting to atrophy, I start flying the 109. I figure if I can get kills in a 109 then I can get kills in anything.
The trick to the 109 is to think of it as a bolt-action gun; fire quick bursts and save your ammo. The MGs are useless so your real measure of ammo will be the cannon rounds. For all models, I bring 100% fuel and a drop tank, because you never know how far you'll have to go to find something to shoot down. Its also a good idea to map your elevator trim to your stick to avoid loss of elevator control at high speed, and to increase turn rate a bit at speed. Remember: WEP on when nose up, WEP off when nose down. If you get slow enough that you can deploy flaps, you're probably going to get whacked by a Spitfire or N1k, but you have a pretty good chance against a Mustang or Spit XIV, depending on attitudes, positions, relative speeds, and pilot skill. Mustangs are particularly vulnerable to overshooting their targets, so as the 'stang flies past, you can hit WEP and get off a quick shot before he gets out of range. Don't forget to use rudder to correct for engine torque.
109F: Short range fighter, works best without gondolas, best forward visibility of the group but can't see out the back very well. You can expect to get snuck up on from behind quite a bit if you don't kick rudder to clear your baffles from time to time. Only fire at or under d400.
109G2: Leave the gondolas at home. Fly it like a 109F. Its a nimble little plane. Great roll rate at speed but will stiffen up if speed gets over 300 or so. As with the 109F, only fire at or under d400.
109G6: Engine torque will really mess with the stability, particularly when using WEP. It'll want to snap to the left unless you apply counter stick and/or rudder. You can consider gondolas, but if you do then you might be better off in a G14. Rear visibility is improved. If you have a problem controlling your speed, then take the G6 over the G14 as it is slightly slower and less likely to nose-plant into the ground if you get stuck in an extended dive. Just remember that if you're bringing gondies then you can expect to pay a weight penalty.
109G14: Gondolas make great counter-balances to the engine torque and also improve your lethality. You'll pay a bit with loss of top-end speed, but I consider this a good thing since the 109 will stiffen as you get fast. Gondolas also improve the cone of fire so you have a little leeway to the left and right of the pipper. You're not going to outrun a Mustang, Typhoon, 190D, or LA-7 anyway (depending on starting speeds and rate of descent), but you still have a shot at destroying them before they destroy you so don't be afraid to engage. The 109 motor has a lot of pull to it with WEP, so it can accellerate a bit better than a Mustang. Its a good idea to use tracers, for two reasons. One, bullet drop-off takes some getting use to, and two, if you find that your quarry is out-running you, you can use the nose MGs to "tickle" your target into turning and allowing you to close the gap, then finish him with your cannons. He won't be able to distinguish MG rounds from cannon rounds.
109K: I haven't flown this one much. I never had much luck with the 30mm when it was a G10 due to my poor marksmanship. I do remember it being nose-heavy so I assume that carried over with the introduction of the K model.
Ok, that's enough to get you started.
