Perhaps the most obvious is to increase precision, which is a function of manufacturing and assembly tolerances, gear tooth surface finish, and the guts distance of the tooth mesh. Sound is also affected by gear and housing materials and also lubricants. In general, be prepared to pay out more for quieter, smoother gears.
Don’t make the mistake of over-specifying the engine. Remember, the input pinion on the planetary must be able manage the motor’s result 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 required will require a larger and more costly gearhead.
Consider current limiting to safely impose limitations on gearbox size. With servomotors, result torque is a linear function of current. Therefore besides protecting the gearbox, current limiting also defends the engine and drive by clipping peak torque, which may be from 2.5 to 3.5 times continuous torque.

In each planetary stage, five gears are simultaneously in mesh. Although you can’t really totally get rid of noise from this assembly, there are several ways to reduce it.

As an ancillary benefit, the geometry of planetaries matches the form of electric motors. Therefore the gearhead can 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 fast acceleration and deceleration, a servo-grade gearhead could be the only wise choice. In such applications, the gearhead could be viewed as a mechanical spring. The torsional deflection caused by the spring low backlash gearbox action adds to backlash, compounding the consequences of free shaft motion.
Servo-grade gearheads incorporate several construction features to reduce 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 tend to be the most costly of planetaries.
The kind of bearings supporting the output shaft depends on the load. High radial or axial loads usually necessitate rolling element bearings. Small planetaries could manage with low-price sleeve bearings or various other economical types with relatively low axial and radial load ability. For bigger and servo-grade gearheads, durable output shaft bearings are often required.
Like the majority of gears, planetaries make sound. And the quicker they run, the louder they obtain.

Low-backlash planetary gears are also obtainable in lower ratios. While some types of gears are usually limited to about 50:1 or more, planetary gearheads expand from 3:1 (solitary stage) to 175:1 or more, depending on the amount of stages.