Prep for Painting Dash

Sorry i couldnt find it in the forums, I know its gotta be here somewhere but cant find it...I was just wondering what I need to do to prep my Dash to paint it...I heard that you have to clean it with some stuff to get all the grease and stuff left over from armorall and stuff like that first...can someone please tell me what product would do this well? or if I need to do something else? Thanx