Best System I know is, handicap the games if the line looks right play it, if it looks off stay away or fade it.
If you don't have time to handicap the games do the opposite if the line looks off - have a look into and try and figure out the why
75% of the line is based on starting Pitching...Bull pens blow games especially in the 1st half of the season until their rotation gets set.
That's why sometimes the line looks off!