From experience, 1) have a blocking diode beefy enough to handle max current with plenty of headroom. If it opens up (or some other part of your connection to the batteries opens) the wind generator will freewheel, and in strong winds (like mentioned by Bay Bridge Sue up above) that will be very fast indeed. Which leads to 2) have a heavy duty double throw battery switch that both disconnects the wind generator from the battery banks and shorts the generator leads together. That brakes the turbine, keeps it from spinning when you don't want it to, and halts a runaway. One of those marine Off/A/B/A+B battery switches can be wired to do this. Happy power generating!
Hornet PMA wind turbine on top of my bus
Burning Man 2003,4,5,6,7,8,9,10,11,12; Desert Carillon, Ulaume's Chimes, Iron Native, Black Rock Solar DPW Crew, Portal Collective
Welder, mechanic, bike fixer, bus nut, furry, SL dancer, and Captain of the Starship Palomino