Stealing 3rd base is something that amateur and scholastic teams should be doing more often. It's all about finding the right opportunities. Consider this posting the first in a three part series about stealing 3rd.
Timing is Everything
Steal on a pitcher who doesn't change his timing to the plate. By studying the pitcher's tendencies, a runner at 2nd can get a huge jump. Look for a few things:
1. Observe how many times the pitcher looks at the runner before starting his delivery to the plate
2. Count the seconds from the pitcher's set position to the start of his motion.
3. Look for a movement the pitcher makes that jumpstarts his motion. Sometimes a pitcher will tuck his chin or bob his head slightly.
The effectiveness of this approach is increased even more when the 2nd baseman and shortstop are not paying much attention to the runner at 2nd.
Rule of Thumb: Don't make the 3rd out trying to steal third. Most likely, you will score from 2nd base on a 2-out base hit anyways so the reward of getting to 3rd is not nearly as great as when there are less than 2 outs. I'm not saying not to steal 3rd with 2 outs. I'm just saying that if you go, you better be safe! If you consider it somewhat of a risk, steal with 0 or 1 outs. Then, you have the added reward of being able to score from 3rd on a sac fly or infield grounder.