So you haven’t changed your strings in a year and your once beautiful shiny frets now have a dingy green tint to them. You wipe and wipe but nothing happens. Here is a simple trick to get those frets back to their original shine. (Note: This tip is not recommended for maple and finished fret boards.)
Take a piece of #0000 steel wool (not sandpaper) and run it up and down the fret board until your frets shine. Take care to cover your pickups and any electronics with masking tape…steel wool can wreck your electronics. If your fret board is really dirty you can steel wool across the frets, but because this is against the grain of the wood, you will need to go back over the whole neck again, with the grain, once you are finished. Now is a really great time to condition your fret board with lem-oil or other conditioning product.
Perform this every other string change, and your frets will always look like new. Play on!