In general, a non-abrasive, non -residue track cleaning method such as club approved blocks, Isopropyl Alcohol or track cleaning car is preferred.
Club approved Blocks are actually very fine finish sanding block which keeps abrasion to a minimum while thoroughly removing tarnish, oils and other debris on the top of the rails. Carefully glide the block over the rails avoiding any layout scenic items such as trees and telephone poles. Do not glide over switches, clean these carefully, gliding in the direction of the switch.
Isopropyl Alcohol can be applied to a cloth material that does not leaves loose strings, and the rails wiped clean. Again, be careful around layout scenic items.
Do NOT use solvents that leave residue such as Goo Gone or other oil based cleaners. Do not use sand paper or track cleaning stones.