First off, Filing frets can be done on your own, but as the last post says, it takes a good eye, and good judgement, but it also depends on how bad your frets are worn, if they are deeply worn re-fret or get someone who has experience to file them, now if they are only slighty worn and you have artistic abliity(in other words a good eye) you can do it yourself, first off you need a shield so that when you are filing you do not sratch or gouge the fretboard itself, now you might be able to get an actually fret filing shield at your local music store.. and if you cannot there is an alternative, get an eraser shield (used by arcitechs and whatnot) this is a thin metal plate with differnt lines and arcs and whatnot cut into it you can guess what its used for, these shield usually have a nice long line cut down the middle , which usually fits over your frets rather nicely with a tiny bit of modification, the man modifcation being that you must trim the excess off the sides so that it fits between your two lowest frets, then you simply get the proper file(i recommened a proper fret file) and start filing now there is certain ways you should file and what not, this in my opinion also depends on how badly the fret is worn, but as the last post says, you need a good eye and experience, but how do you get experience, find a really cheap guitar at a flea market or something, even a chaep neck or whatnot and practice this way you are not hurting your actually axe, this is how i learned, now i am not professional by any means, but at the same point this is something that every serious guitarist should at least know a bit about, if anything it lets you understand why it is so expensive to get done. and if you don’t feel comfortable doing your self get it refretted or at least replace the frets that are badly worn and get them filed to size..this is only the ramblings of a guitarist on a tight budget who leart the hardway, if you try it and fuckup, sorry but those are the risks