Tips to Use Gyrocopter (Dota2)

• Rocket Barrage is incredibly powerful against a single enemy, but its damage falls off dramatically if there are multiple targets. Position yourself to make the best use of it.

• Homing Missile is a great harassment tool. Place it behind your allies to prevent the enemy from destroying it before it starts moving.

• Flak Cannon allows you to harass enemy heroes from a great distance, or force them away from the creeps. An early point should be considered if you are taking the solo mid-lane. However, it does push the lane and may open yourself to ganks.

• Using Flak Cannon early (before you use the attacks) will lessen the cooldown on your next cast.

• For maximum effect, cast Call Down in conjunction with your Homing Missile's impact or an allied disable.

• Aghanim's Scepter will allow you to snipe fleeing enemy heroes with Call Down. It can also be used to assist or deter pushing. 

source: http://dota2.gamepedia.com/Gyrocopter