You don't have to worry about using isopropyl (rubbing) alcohol. Official cleaning kits sold back in the day were actually just repackaged rubbing alcohol. The only reason the publishers warned against using rubbing alcohol was because they wanted to trick you into buying the official cleaning kits.
Plus they wanted to cover their asses in case somebody did something REALLY dumb, haha.
Rubbing alcohol is my default method, but I do love to use an eraser if rubbing alcohol alone isn't enough to get a game working. I use those big, rectangular elementary school erasers that are usually green or pink. If it's too thick for the job (if I want to clean the contacts of an NES game or something), I just slice the eraser in half.