Hands down, this the favorite studio activity of the year.
At the first lesson or class after March 21st, I simply put some lemon oil or rubbing alcohol on cotton balls or small pieces of paper toweling.
The lemon oil is to clean "anything that's brown and shiny," andthe rubbing alcohol is to clean "anything that's black or silver."
I have been doing this for 30+ years, and am still amazed by how much the children enjoy and take pride in the shape and beauty of their most prized possession. Luthiers will tell you all that is needed is a daily wiping with a clean, soft cloth, but this once a year deep-clean brings the instruments back to their just-bought shine.
BTW, Things 4 Strings accessories are "dishwasher" safe -- or good with just a little soap and water!