Perhaps the most obvious is to improve precision, which is a function of manufacturing and assembly tolerances, gear tooth surface finish, and the center distance of the tooth mesh. Sound can be suffering from gear and housing materials in addition to lubricants. In general, be prepared to pay out more for quieter, smoother gears.
Don’t make the mistake of over-specifying the electric motor. Remember, the insight pinion on the planetary should be able manage the motor’s output torque. What’s more, if you’re using a multi-stage gearhead, the output stage must be strong enough to soak up the developed torque. Obviously, using a better motor than necessary will require a bigger and more expensive gearhead.
Consider current limiting to safely impose limitations on gearbox size. With servomotors, result torque is certainly a linear function of current. So besides protecting the gearbox, current limiting also protects the engine and drive by clipping peak torque, which can be from 2.5 to 3.5 times continuous torque.
In each planetary stage, five gears are at the same time in mesh. Although you can’t really totally remove noise from such an assembly, there are many ways to reduce it.
As an ancillary benefit, the geometry of planetaries fits the shape of electric motors. Thus the gearhead could be close in diameter to the servomotor, with the result shaft in-line.
Highly rigid (servo grade) gearheads are generally more costly than lighter duty types. However, for speedy acceleration and deceleration, a servo-grade gearhead may be the only wise choice. In such applications, the gearhead could be seen as a mechanical springtime. The 
torsional deflection caused by the spring action adds to backlash, compounding the effects of free shaft movement.
Servo-grade gearheads incorporate several construction features to minimize torsional stress and deflection. Among the more common are large diameter result shafts and beefed up support for satellite-equipment shafts. Stiff or “rigid” gearheads have a tendency to be the costliest of planetaries.
The type of bearings supporting the output shaft depends on the load. High radial or axial loads generally low backlash planetary gearbox necessitate rolling component bearings. Small planetaries could manage with low-price sleeve bearings or additional economical types with fairly low axial and radial load capacity. For larger and servo-grade gearheads, durable output shaft bearings are usually required.
Like the majority of gears, planetaries make sound. And the faster they operate, the louder they get.
Low-backlash planetary gears are also obtainable in lower ratios. Although some types of gears are usually limited by about 50:1 and up, planetary gearheads extend from 3:1 (solitary stage) to 175:1 or more, depending on the number of stages.