Here's some good stuff from FanGraph.com...

1. Never put the tying or go-ahead run on base.

2. Play for the tie at home, go for the victory on the road.

3. Don’t hit and run with an 0-2 count.

4. Don’t play the infield in early in the game.

5. Never make the first or third out at third.

6. Never steal when you’re two or more runs down.

COMPLETE LIST & ANALYSIS

MLB baseball strategy, baseball unwritten rules