Never imagined that I had a ritual but the fact is that every time that I purchase a NES game the first thing that I do is a cleaning procedure which consist in opening the cartridge, clean all the pins with an eraser then apply a metal polish cream to them meanwhile I take my time to clean the outside of the cartridge, label first with some baby wipes, then the rest of it with some alcohol to remove the dust, for the markers a white eraser is my best pal after all of this I test the game in the console, really hate to blow the cartridges, never did this when I was a kid cause always used cotton swabs with alcohol but they only solved the problem for some days.
Now that I think so have spent a lot of time repeating this procedure cause have done this with more of 100 cartridges