Simple as 1, 2, 3.
If you buy a new car, do you leave it for 4 or 5 years before you clean it? No!
You're out there at least once a week with a bucket of water and rags cleaning away all of the muck and grime.
So too should you clean your guitar. I would not recommend a bucket of soapy water but a few clean cloths and a bit of polish. Clean the strings after playing and remove all of the grease from your hands and that means clean the strings too. Move those switches and knobs, don't let them get caked in muck and become scratchy.
You don't have time?
Drop me a line and we'll make a date for you to drop it off and get it cleaned and spruced up.
Just another service I offer.