There's an approved main gear mud flap for the 208 which prevents stones flicking up from the tyres into the elevators. But in over 15 years of operation we've never had a stone flick into the wings!!
I agree with Lilfyboy's advice - many operators carry a broom in the pod to sweep under the prop blades to prevent prop damage on start up, and to avoid stone damage on the prop during taxi, and take-off use a short rolling take-off while you apply full-power. Keeping the aircraft moving gently forward before fire-walling it is a good way to keep the prop doing its job. Beta, flat pitch, and surging on loose surfaces is not going to help.
But I don't know of any technique to avoid stones into the wings - never seen it happen..... The elevator sometimes takes a few chips but they're generally negligible if you have a policy of looking after the plane in the hope that it will look after you when you most need it!!