I recommend using a microfiber or glasses cleaning cloth to wipe the face of your pins.

Metal pins in rose gold or silver tend to tarnish faster than other variants, such as gold or black nickel. I recommend cleaning them at least once a year, as the tarnish can blacken the pin. 

Do not keep pins that feature epoxy in direct view of sunlight as uv light causes yellowing of epoxy.

Outside of that, if you're trying to remove excess screenprint or screenprint imperfections you can use acetone (nail polish remover) or very strong isopropyl alcohol with a q-tip or small cotton ball. When doing this please be careful as once screenprint is removed it cannot be undone!!