These are my cues for attention, works well!
T: 123, eyes on me!
S: 1-2 eyes on you!!(Ss must look at you and point at you when they say this line)
This one just came up on my mind when I teach 2nd graders:
T: On my count to five, close your book.
S: 1-2-3-4-5, pa!( to stand for the noise of closing the books)