I don't HO(because silat told me not to a long time ago)
I would suggest starting here. All the BS about how head on shots are bad is a pet peeve of mine. The goal of air combat is to make bullets from your plane hit their plane. The angle of said shot is completely irrelevant. Yes, it is generally not a good idea to go for the head on shot, but 99.9% of the people whining about it have no idea why. It has nothing to do with some "code" ... it is because you are wasting the opportunity for a lead turn. The goal at the merge should be to get separation to allow an aggressive lead turn back into the opponent, or if you believe they have significantly more speed than you, to turn away from them and get them to overshoot. If the opponent wants to go for the head on shot you can gain an easy 45-90 degree on him right at the merge and gain the upper hand. Once you master the lead turn, you will be complaining if people DON'T go for the head on shot!
With a well timed lead turn:
- It is impossible for an opponent going for a head on shot to land bullets on you (the trick is to roll slightly as you think they are in guns range). In fact, if he is determined to point his nose at you you can control which direction he will turn. usually it is a good idea stay below them and make them turn nose low, since their turn radius at the bottom of the turn will be larger than yours.
- You can gain a huge angular advantage at the merge, putting the opponent at the disadvantage.
The trick is figuring out which one of these 3 you are facing:
- Someone who goes for the head on shot ... (noob who doesn't understand lead turns)
- Someone who avoids the head on shot because it is "bad" and the mean people on the forums will make fun of them (noob who doesn't understand lead turns)
- Someone who avoids the head on shot because they are aggressively turning at the merge (you should watch out for these people ... and strive to become one).
I think that there are three separate sets of skills needed to be successful in this game. The first is being able to out manoeuvre someone, the second is being able to put bullets on target, and the last is fighting in a crowded airspace.
In the main arena I think the biggest trick is to keep track of the situation around you. It is pretty rare to find yourself in a 1v1, it is more likely, especially during peak times that you will have a numbers advantage or disadvantage at any moment. It is important to regularly check the darbars in your sector, and all the sectors around yours, keeping track of who has the strength in numbers, who had the alt advantage at that moment, and regularly looking around. It also helps if you choose to attack a base that is isolated on at least one side, for example if it is on the coast. That limits the number of directions you have to keep track of. I probably have the map open more than 75% of the time as I am flying, trying to get a feel for where a fight is going to go. Every 10-20 seconds I will put it away, look around, then bring it out again. This is also a good way to get a feel for when a tasty vulch is about to develop!
Also take note of landmarks and the sun when you are entering a fight so that you can dive away from trouble in the right direction without having to open the map. Trying to dive away but going in the wrong direction is a sure way to get ganged in this game!
More than anything else, I have found that getting films of expert players and watching them from as many angles as I could helped me more than anything else. In particular, taking note of flaps, rudder, power changes, etc. Another useful thing that I still do occasionally is to go offline and shoot drones for 10 or 20 minutes for all different speeds and angles.
Another tip is to take note on the E6B page of your plane's weight. Look at it with full ammo and fuel, half ammo and fuel and almost empty. In some planes the difference can be over a ton. It is amazing how much of an affect that weight has on the performance of the plane. Weight is everything! I have out turned spit 16s in a P47 that had almost no ammo or fuel left. Whichever plane I am in, I usually have target weights for each type of flying. For example, at X weight it is high speed passes only. At Y weight I can turn aggressively to get kills, but I try to keep my speed up and be picky about who I choose to attack. At Z weight I can get down and dirty and make speed sacrificing turns (usually just the last couple of minutes before I am out of fuel and ammo). If I am headed home and get bounced and decide that I probably wont see anyone else, I will cook off most of my ammo to lighten the plane, just leave enough for the 1 kill. As I said, weight is everything! It also helps to use a bit of detective work to judge how heavy your opponent might be. For example, if you are near their base and they are just taking off, you can be pretty confident that they are fairly heavy.
I hope this helps. More than anything else, practice, do some reading on tactics and ACM on the various websites (like the excellent netaces.org), and watch a lot of films!