They do several things. First of all, they will often choose to put their satellites at altitudes that have less congestion, less debris. That's one strategy, where you position your satellites and your satellite system.
Some operators build shielding into their satellites and build in redundancies. Instead of having just one electrical wire connecting two components, you have two electrical wires, so if that tiny paint fleck of space debris were to cut one of the wires, you'd have a backup that would keep the satellite operational. The more shielding you put in and the more redundancies you put in, the greater the cost of your satellite.
One of the big problems today is that some operators, led by SpaceX, have adopted the consumer [Technical difficulty—Editor] thousands of mass-produced, low-cost satellites with no redundancies. Then they have an operational life of just four or five years. Just like your cellphone, they throw it away after four or five years and send it into a re-entry trajectory.