This is what I am saying, because you are listening, you are not always looking and it isn't because your not doing what your supposed to..
I have this system where each of the 4 people in front (we are all singers) have an indicator push button. Push the button and a tiny LED flashes back by the board. 4 singers 4 color lights. Sound guy knows instantly who to look at and figure out what they need. Simple solution for band and FOH. In our case, most everything gets worked out in the first couple of songs and the rest of the night they sit, but they certainly come in handy. No announcing it through the mic or doing arobics on stage to get FOH attention. Push a little momentary switch, light comes on back by the board and bobs your uncle, you get what you need. Attention from FOH..