This is another very common question whose answer is dependent upon what is being cooked and how hot the fire is. Perhaps the best (though somewhat ambiguous) answer is: The meat should be turned soon after it begins to turn color (i.e., just as browning begins to occur) and after the meat no longer sticks to the surface of the grill any longer. Turning frequently will not hurt or harm the meat in any way, however it is best to try to obtain a good cooking on each side, prior to turning it over.