Clean your bass regularly with polishes offered by companies specifically for the guitar application. The beauty of our fine woods will be enhanced.
Dirt , Oil and Grime of your hands can build up on the fretboard. So dress the frets every time you change strings. This is bad for sound and reduces the lifespan of your strings. Use a very soft-bristled brush and a little soapy water, and I make sure to dry well after cleaning.
Time by time clean all metal parts of your guitar with a good metal cleaning compound. Chrome and nickel are notorious for tarnish and corrosion, especially in humid environments,
And last but not least -PLAY YOUR BASS!!! There is no better way to keep your bass in tip-top shape than to play it every day.