PfD's point about the small profile is a very important technique all new players should be aware of, and taught by their trainers/squadmates. It's probably the most important thing to be aware of when on the defense in any plane - if it looks like your opponent is going to get a shot at you from some angle that isn't behind you, roll and put your wing right on him, or as close as possible, and continue putting G's on your plane to make your plane move through HIS site at a trajectory that is hard to hit. It isn't always easy to do depending on the situation, especially in a 2 or 3 vs you fight, but once you get the hang of it, it'll increase your survival by a huge margin.
Also, telling new players to use the climb power of the 109 is a bit vague IMO. Just putting the nose up and hitting WEP can make you an even easier target in may situations, it's critical to know when and where you can use your climb advantage vs another plane, and it's very dependent on your opponents current E state, direction of flight compared to yours, and of course his distance. An F4U sweeping in behind you when your nose is level, and at d500 or d700 or so, putting your nose up and hitting wep to climb will make you a very, very easy target, so just be aware of when you can and cannot get away with spiral climbing on your opponent. You almost have to wait until he is very low on energy or at a much lower E state than you, that or you need distance separation, before initiating a climb on him. That IMO is the real trick to using E fighting planes like the 109, knowing when you can actually use it against an opponent, and it will only come through practice, and a lot of failure, unless you get a really good trainer who puts you through some pretty good 1v1 examples. Watching your opponent, particularly the distance marker, and the + or - to tell if you're gaining E or losing E compared to him, will begin to tell you what his energy state is at. When you see it settled, or a + when he's behind your 3 to 9 line, you know you have an advantage - this is a good time to try and put your nose up with Wep on and try to force him into following you, something he can't match from the stats of the planes in this example. If you're patient, and keep the pressure on him this way, he'll be forced to either turn away, or will stall out trying to match you, or will simply start to fall further behind you as you can height and E on him, giving you the chance to turn things around.
There are some great 109 guys who can help you begin to figure it out, guys far better than I am at teaching and doing this, any of the Muppet or other L/W 109 squads have guys that will take you into the TA or DA and in even 30 mins, you can probably double your skills from getting some pointers and example fights.
