The best start to limited maintenance is to choose your material wisely. DIY says to avoid cable not purchased from reliable sources or online from generic websites. Even though you are a DIY consumer, you can still purchase the same materials contractors trust.
Maintaining Cable Railing is not much different than maintaining a nice car. The majority of discoloration found on cable railing will be in oceanfront locations where the most corrosive natural ingredient is found in abundance, SALT! The difference between rust and discoloration is that rust deteriorates a material and discoloration is an action caused by a foreign material, usually salt. The salt and discoloration wipe off, but the elements remain unless washed off.
Limiting maintenance begins the day you install your cable railing by giving it a thorough washing immediately after install with a car wash soap. Skipping this step because all looks new and shiny is a big mistake. Stainless steel will actually improve over time by building a stronger chromium oxide layer. Since stainless steel depends on Chromium oxide for its primary protective layer, the cleaner the railing is kept in the first few months the better the material becomes.
The nature of cable with several strands twisted together makes it a perfect hiding place for work site residue, dirt, solvents and other contaminants to hide and trap salt regardless of treatments and cleaning. It is nearly impossible to remove all contaminants on and between the cable strands until the product is installed.
The biggest part of maintenance is simply fresh water rinse, but when cleaning is required it can be done with nothing more than a good car wash soap, a sponge or rag and fresh water, but a recommended enhancement is to use a pressure washer on the cable which does a great job of flushing out residues along with job site dirt and handling grime. A once over with a hose or power washer before cleaning with soap will allow the soap to better penetrate the cable. Be sure to flush out nooks and crevices along the way.
Should you encounter light staining or have an unfortunate accidental nick in the material, an easy field passivation kit will allow for quick removal. Always follow instructions when passivating.