Posting this again incase anyone wants to know:
Flight tips:
Hold down the fire button when using missiles. They will automatically lock on to targets in your scope. Release the fire button to fire.
Double tap and hold R2 for a speed boost. Useful to get somewhere quickly or avoid locked missiles (turn around buildings/hills).
Hold L2 & R2 to execute a powerslide.
If you're going to use sticks and not motion control, play with Pro-Flight active. It takes a bit of getting used to but definitely makes you much more agile in the air, also makes those silly newbs doing constant barrel rolls easy pickings. Start your own password protected game and learn.
Learn where the chaff and health pickups are in the air when flying. Those two items are your lifeline and will make the difference of staying alive for 2 mins or 20.
Beware the Ground-to-Air guns and missiles. They will shread your warhawk almost immediately. If you want to get risky you can try to get behind them and use a large homing missile, otherwise just land as close as you can and chuck grenades.
The stealth powerup is usefull for flying around the map grabbing all other powerups without interruption. When you start using your weapons the stealth will instantly deactivate so use it only when you're not going to fight.
Tow Missiles is the most powerful weapon for a Warhawk. If you see a shockwave go off somewhere on the map that's the Tow. Know where they spawn. You can be a real rat bastard if you keep picking one up, hiding, and killing groups of people without anyone knowing where you are. Great to take out a well defensed group.
Small tip for Air-to-Air combat. If I'm flying against someone that is somewhat skilled, I like to fire a single swarm missile at him just so that he gets rid of his chaff, then load up ten more for the next slavo.
Land Tips:
There are no parachutes and you cannot jump out of a plane that does not have it's landing gear down (automatically extends when Warhawk is in hover mode and close to the ground). Keep this in mind if you are going to jump into a Warhawk in passenger mode. You may be taken on a long and stupid ride unless you really trust the guy.
Infantry weapon is as follows: Knife is most effective for extreme close combat (one hit kill), guns/flamethrowers are most effective for close range combat, machine gun for medium range, sniper for long range. Rocket launchers will lock onto Warhawks, Tansks and I believe Ground-To-Air missiles/guns. Know your distance and when to use what weapon.
Binoculars are used for calling an airstrike. Just "shoot" the binoculars to a far distance and wait until the timer reaches zero. One hit kills anything in its radius.
Equipping the knife will make you invisible to enemy's radar. That is a big deal.
Grenade on a soldier is a one hit kill on contact.
Vehicle Tips:
Tank shots can kill Warhawks in one hit. If you see a hovering Warhawk don't hesitate to aim and shoot.
Tanks can carry two players, one driver and one passenger. The passenger can pop in and out of the Tank hatch with the Triangle button (IIRC) and fire on anyone in range using an eqquiped gun, machine gun or missile launcher.
On Jeeps: Hold down L2 & R2 to cause a skid. Useful for quickturns and just looking/sounding cool. A jeep can hold three players: Driver, Gunner and Passenger. The passenger is a gimp that can't do anything but sit along for the ride. R1 is the jeep's horn. Annoy at will.