The only time I'd bother betting on a series is if it's the playoffs.
In baseball during the regular season there's simply no point. It's a 162 game season, there's a lot of stretches where good teams just go through the motions, especially when they're on the road. Really, my biggest strategy is to base my analysis on what the Las Vegas line is inviting the bettors to do. When you do this every day for years you start to have a good idea of what a line or odds are gonna be before they're even released, and if you see a team that is overvalued, that's a good indicator to bet on the team.
Of course, good teams are overvalued all of the time, and that's not what I'm talking about here. An example would be the wager I won last night. The Patriots were only a 3 point favorite against Jacksonville and every gambling degenerate was betting on the Patriots simply because of the name. And again, today, I see no logical reason why New York Giants should be a 4 point favorite against Pittsburgh in a pre-season game. That shows me Vegas has total confidence in them winning.
This strategy of mine only works if you have a vast feel for the lines though.