One method is to mix some baking soda with water until it gains a pasty consistency. Then rub it onto the affected area.
Finally, get some vinegar; I think ordinary vinegar should be fine, and pour it over the baking soda until it's gone.
Apple cider vinegar is sometimes used on its own as a sting remedy, but the above method seems to work better for me personally.
I've read that lavender oil also works, if used in small amounts on the sting area. I haven't tried it myself though.