Starters that are not subject specific.

I was reading one of the posts and someone suggested that to get the students to settle down they have a starter on the board. Not a problem for a regular teacher as i have also used this before. My question is since we cover different subjects, what starters can we use that are not subject specific i.e can be relevant in any subject. I must say i do struggle with getting students to settle down so am thinking this may be the way to go but dont know how. Any help will be highly appreciated. Thanks