Here is an obvious tip…wash your hands before you play your guitar!
Super obvious, but, I bet you don’t do it all the time!
If you are on a budget or a beginner that doesn’t know how to change your own strings…your strings need to last you for as long as possible. The more filth and muck that get on your strings the shorter life they have.
The worst offenders are often kids. Guitar teachers will have surely seen this one…the occasional student walk into class with orange finger tips? Covered in gunky cheese powder from some kind of crackers…yuck! Or something even stickier or grosser…
For the rest of us it is just daily activities that keep our hands less clean than they seem to be…so scrub up and save a buck or two on strings!