Generally, the best piece of advice you can get is don't fly alone. The D9 can fly alone, as long as the pilot is extremely cautious. Even with the D9 you really have to stick with straight Boom and Zoom (think pendulum type attacks, an aggressive E style of fighting is not possible in the 190 like it is in the 109). The A5/A8 are to slow, and they can't accelerate or climb their way out of trouble like a 109 can.
If you get stuck in a situation where you are facing a slower plane like a spit or N1K2 that has more speed than you, there are a couple things you can do. If you are 1v1 with him, you are OK. If you are around a pack of them, just bail because you are going to die. The first thing you need to do is get him away from his friends, so you will go into a relatively shallow dive to get your speed up to something approaching his. Usually 350 mph is fast enough to keep them from closing on you. Next, you actually want to put him on your tail, and get him away from his friends if at all possible. If his friends decide to come to, and they are all slower than you, just keep running. If just the one guy decides to follow you, you can engage. What you will do is from a distance of 1.5k or so, go into a nice gentle turn to one side. If he keeps heading right at you, tighten the turn up as he gets closer. Ideally, he will be coming straight in doing about 350-375, and you will be pulling about a 4-5g turn coming across his nose. Now, you basically make a barrel roll around him as he comes in shooting. Going from your turn, you roll wings level, and pull up. As he passes under you, you roll to put the top of your head where he will come out (lift vector), and pull straight back down. If this is done correctly, you will be seeing him fly past through your gunsight, but you will be upside down. Don't bother to roll right-side up, just learn how to shoot inverted. Now if Mr. Spit decides to pull hard back into you and start a flat scissors, you will have maybe 1 or 2 more shots at him before he slows down enough to kill you. Hit those shots. If he decides to zoom, you will basically start the process over, so you run to get your speed back up, then try to sucker him in again. Do not follow him up in a zoom, because you will be roped and killed.
The 190 is really a one trick pony in a fight. You have to learn how to hit any shot you can get. The 190a5 can manuever relatively well, but the firepower is awful. The 190a8 has decent firepower, but the manueverability is awful. The D9 has awful manueverability and awful firepower, but it is fast at least.
For the 190d9, Mandoble is probably the best pilot to learn from if your goal is not to die. He flies Boom and Zoom, but he flies it reasonably aggressively. I fly much to aggressively in the D9 to be any good in it.