Building familiarity with the game's controls will get you off to a good head start, and mastering vehicle movement will ensure that you remain a formidable presence in late-game confrontations.
You will need to use the WASD keys and your mouse to control your character's movement. W moves your character forward, S moves them backward, and A and D allow them to strafe. Use your mouse to control where your character is looking.
Vehicle movement is similar to that of your character. Use the WASD keys to control your direction, and use your mouse to control where you're looking.
Compared to ground vehicles, airborne vehicles are a little more complicated to control, and involve maneuvers such as lift-off, steering, hovering, descending, ascending, and landing.
Lifting off: When piloting a helicopter, hold W while on the ground to begin liftoff.
Forward: Once the helicopter has lifted off, hold W and slide your mouse to tilt your helicopter and move forward. Don't tilt your helicopter too far forward, or you'll crash!
Reverse: Hold W and slide your mouse to tilt your helicopter backward. Just like when moving forward, don't tilt your helicopter too far, or you'll crash!
Steering: Slide your mouse to steer, or press the A and D keys to turn quickly.
Hovering: Press the H key while piloting a helicopter to hover.
Descending: Tilt your helicopter's nose forward to descend.
Ascending: Keep your mouse mostly neutral and hold the W key to climb. Helicopters can only ascend to a certain altitude, at which point you will not be able to ascend any higher.
Landing: Once above a landing site, press H to hover, wait until your horizontal speed drops to 0, then press S to descend until you land.