Strings!

I presume you are talking about acoustic here?

In general the thinner the string the less noise you get when you slide your fingers around, but then the strings are quieter all round the thinner they get. I personally use 10's (the top E is 1 tenth of a milllimeter). Also you can buy coated strings which help somewhat.

You can buy products that you can use to help with the squeak but more importantly it is technique. When changing chords try to lessen the contact you have with the strings to the point that you are barely touching them when changing shape. This takes some doing ( doesn't everything!) but it is just a matter of practise.

Listen to any acoustic trak and you will nearly alays hear some squeak. I listen to John WIlliams alot and even this supremo cannot get rid of it totally.

Lastly, I have found that it always sounds worst to the player than the listener. We are right on top of the fret board and hear every little noise. Try recoerding yourself from the distance that others would hear you and you will find it is not that bad. Other than that, as always, practise makes perfect. Happy playing. Adios.

Shaun