To maintain a constant speed and altitude, the pilot must use the three main flight controls in a coordinated way by making small adjustments when necessary.
In other words it's a straight and level flight:
The straight and level flight is a flight at a constant altitude, at a constant heading, with a constant airspeed in co-ordinated flight
Note that in this part, we will see the basics of straight and level flight. To go further and understand how to use flight instruments during this practice, refer to the following article: Helicopter Instrument Straight-and-Level Flight
To maintain a constant speed and altitude (but also a constant heading) during the flight, the pilot must use the cyclic, the collective and the anti-torque pedals at the right moment and only if necessary to resume the flight at the desired altitude or speed. Note that even small changes in any of these two parameters must be corrected to maintain a constant flight in terms of altitude and speed
To that end, the pilot must be attentive to the reactions of the helicopter and react by using the flight controls in case of changes of altitude, speed or heading