Here's a few things I've learned over the years. Some might have already been posted but they are worth repeating.
1. Fire only one set of cannons at a time unless you are attacking bombers. 4x 30mm cannons is overkill for everything except bombers. If you fire only one set at a time, you double your firing time. Also, achieving consistent success with the 30mm cannons takes time. The ballistics are horrible compared to Hispanos or .50s. They take some getting used to.
2. Spread out the convergences for the cannons. If you spread them out it will increase the chances of a hit when firing all four.
3. You don't always have to fly at full throttle, especially if you are on your way to/from combat. I've found that 7500 RPMs will keep you fast enough to stay safe and will also conserve fuel.
4. Never land or take off from a base that has dar in the sector unless you are damaged or bingo fuel and have to make an emergency landing.
5. ALWAYS chop throttle and watch your speed when diving. There's no worse feeling than the feeling you get after you auger a 262, I've been there.
6. If you get an oil hit, but the engine is still working, shut it down and save it for landing if you can do so without putting yourself in danger. It is very difficult to land a 262 on one engine, especially for less-experienced 262 pilots. If you must land on one engine, try to make small throttle adjustments while on final or else you could go into a spin.
7. Make sure you adjust your views so you can see everything clearly. You have to keep your SA up at all times in the 262. Watch for planes that have an altitude advantage on you because they likely will do anything they can to shoot you down.
8. Pretty much every plane that has the chance to HO a 262 will do so. Don't let it happen.
9. Never attack a bomber from dead 6 o'clock. It's the best way to get yourself killed. Try slashing attacks from above or below or come from the front or sides. Also, make sure you leave yourself enough time to get out of the way. Collisions are a problem when flying the 262 simply because it is so much faster than everything else. The closure rates could be up to twice as fast as they would be if you were in a prop fighter.
10. DO NOT go near ships, strats, or HQs. The puffy ack has screwed over many 262 pilots. Also, if you go near the strats or HQ, you likely will see 163s. There's no escaping a 163 unless you run them out of fuel. They are vastly superior to the 262 in every way except for flight time.
11. Don't get slow when there is enemy around. There's pretty much nothing you can do in a 262 if you get caught low and slow.
12. Be careful when shooting while there are a lot of friendlies around. You DO NOT want to earn the special 262 achievement.