First you must realize that a poorly assembled, or trimmed helicopter may not even start or get off the ground let alone fly.  There are many parts that are constantly moving when the helicopter is in flight and each and every one of these have to be meticulously cared for at the beginning and the end of each flight.  Especially around the swashplate, and main rotor where most everything should be in balance.

For those who don't yet have a helicopter and want to know how high can it fly.  The answer is, as far as you can see.  Fly it past that distance and you wont see it again.

Assemble helicopter as per its instruction manual.

Make sure main rotor is balanced.

Strap on the training gear.

Review your setup.

Check all bolts, check all screws, check all fasteners.

Is your gyro operating in the right direction (does the tail servo try to command the heli to move to the right when you rotate the helicopter to the left). Nasty surprise if not.

Are all control commands operating the proper control surfaces in the correct direction (does pulling the throttle stick down really decrease the throttle).

Where is your CG.  Check it by putting your fingers under the flybar CLOSE to each side of the main mast.  CG should be right under main mast or slightly forward WITH TANK FULL. (you can use skids alignment to floor as reference).

Are your gears set with proper mesh.

Is your clutch set true inside the bell.

Is antennae in good location away from engine, metal parts, servo leads, and battery leads.

Check your batteries

Check your frequency

Check radio range

Check all your switches

Adjust collective pitch so helicopter will not fly more than a maximum of 12 inches above ground.

Adjust main blade tracking

Turn off your gyro and adjust tail rotor pitch control rod until helicopter will liftoff without favoring one direction.

Turn gyro back on and adjust to maximum gain attainable before tail starts hunting (not locking into one position).

Check batteries, fuel, frequency, and radio range before each and every flight.

Be very proficient in hovering before taking off training gear, or flying above 12 inches off the ground.