I usually wipe the track down with a damp cloth, wipe the rails over with WD40 to remove any excess grime, this is the most time consuming part as I usually keep on wiping them down until no more of the black stuff (carbon build up I think) is left. I usually finish off with some Inox on a rag applied with the one finger over both the rails. I have read here on the forum that Inox is available in the UK but can't remember the distributors name. I don't clean the rails as much as I usually just give the track a wipe over with a damp cloth to remove any dust and will then apply some Inox to the braids and give that a run around the track. I'm quite slack really as I will usually set a car or 2 on the digital APB to just run a few laps and clean the braids every now and again until I'm happy that the braids aren't picking up any more carp from the rails. Works for me and I'm sure others all have different ways of keeping their rails clean. Best thing I ever did was get hold of a spray can of Inox MX3, read about here on the forum and found out that it was an Aussie product, had a can half an hour later, about time I could actually go round the corner and get something I needed for the track instead of getting it shipped in from the UK.
Matt
Matt