You don't have to remove the strings just loosen each one enough to lift it out of the nut and off the bridge. Clip any hairs that might have developed. I use a little bit of rubbing alcohol and a paper towel to remove the gunk, it also removes built up rosin if that's your thing. Next I use mineral oil and a light kitchen scrubber on the playing length and then wipe everything off really well with a clean paper towel. Bring the string up to tension and play it! Depending on where you live you won't have to oil them every time.
VERY IMPORTANT!! If you use a bow only oil the strings well north of the end of the fingerboard, rosin and oil do not mix!!
-J
An alternative is to use vodka or 'shine, especially if you need to clean your other guts at the same time.
