This is going to go against all the other advise you'll get. Don't clean it. Wait till the factory grease wears off then clean it. That's what I was advised to do by the gun store when I got my G19. I have made many range trips without a hickup. It's a Glock and it's rugged. Field strip it and look at the slide. You will see the factory grease on a few parts of the slide. It takes a while for it to wear off.