If you are having trouble flying the hawk as you keep being hit by swarm missiles or cannot evade an enemy in general, here are a few tips:
1) Use the map environments to your advantage. Weaving through the surroundings can help you to evade enemy lock ons as well as make the enemy lose your tail.
2) R3 triggers chaff. This can help you evade a large amount of missiles in one go by making the missiles lose their lock on you. Beware, chaff takes a certain amount of time to reload.
3) Powersliding (R2+L2) plus toggling the L3/R3 can be used to avoid enemies locking on to you.
4) Keep your health high by obtaining the red hawk health spawns in the map and by also landing your hawk by transforming into a mech and repairing the mech with the Welding Torch.
Also, as the hawk's damage resistance and power has been reduced heavily, avoid landing close to lots of enemy troops as this can be a difficult situation to get out of alive.
To kill troops, many experienced flyers use the "dive" technique. This involves boosting your plane very high over the enemy base, turning towards the ground and firing swarm/homing missiles and shooting the MG at a target troop while simultaneously holding L2 which slows your hawk. Use chaff to make enemy lock ons lose their lock.