Be wary of public teams:
Major League Baseball's most popular teams, such as the Yankees, Red Sox and Dodgers are always going to be popular with the casual bettor which can result in them being underpriced in the betting markets as the bookies know they will still attract bets even if they do not represent value.
Another area where this can pay dividends is with the run totals in games between two winning sides. Given the tendencies for the public to gravitate towards winning sides and bet the 'over the total' for these games, it can often be artificially inflated. Games between two sides with winning records have stayed under the total 58% of the time over the last five years.
Pay attention to the weather:
It always pays to check the weather before placing your bets, particularly which way the wind is blowing. Games, where the wind has been blowing in from the outfield towards home plate at five miles per hour or more, have gone under the total more than 55% of the time in the last 12 years.
If the wind is a factor then you also want to be aware of the tendencies of the starting pitchers. Pitchers who produce more flyball outs will thrive when the wind is blowing in but are vulnerable if it's going the other way.