This is a somewhat complicated topic and I'll tell you why. Back in the days of cartridge gaming, we'd blow in the cartridge if it wasn't working. They often got dusty and we assumed that this was the best way to get dust out. Literally everyone did this. The funny thing is that the cartridges explicitly state that you shouldn't blow in them. It's the worst thing you can do. Oh, well. You live and learn.
My friends and I used to use Q-tips and rubbing alcohol to clean our cartridges. You dip the Q-tip in a little bit of the rubbing alcohol and then rub it on the inside of the cartridge. This is allegedly a better way to do it. Keep that in your back pocket in case you ever want to bust out your old console.