If you blindly bet home dogs of 7.5 or more, you will do well. If you use power rankings, and play only half of those home dogs selectively, you can hit 60% (although you might only have 7 or 8 plays in a year).
As far as laying more than 3, that is almost assuredly a way to lose money. I would expect a lot of small favorites to be profitable this year (like last).