There are a number of things one can do to ensure they get the longest life possible from their mixer. 

Ensure you keep the mixer in a cool area with a relatively low humidity.  Warm areas can help to increase heating within the mixer, and moisture within the mixer can eventually cause short circuiting.  It’s also advisable to keep an area of about half a foot or more from the back of the mixer clear to ensure any cooling fans can function correctly.

When you won’t be using the mixer for an extended period of time, place a large cloth over the face of the mixer as to help avoid any dust settling on the mixer.  This will ensure dust does not enter cracks and creases in the board.  If your mixer does become dusty, use a soft, dry cloth to wipe the mixer down.

Ensure the mixer is placed in an area where the face of the mixer will not be knocked around.  This will ensure the different controls (VRs, faders, etc) do not become damaged and unusable.