Install the radio gear. Remember, the radio gear normally does not come as part of an ARF kit. Hook the radio gear to the servos. Adjust the servo linkage according to instructions. Install the gyro if you've purchased one.
Most kits have space for installation.
Tie down the wires to the frame. Mount the switch to the radio gear away from the engine exhaust port. Pause and review your work, going completely over the kit to make sure all nuts, bolts and other fasteners are secure. Mount the rotor blades on the rotor head exactly 180 degrees apart. Balance the rotor blades.