The line doesn't mean shit. The line is only a factor about 17% of the time. Getting the BEST line might give you an extra 1.5 to 2% edge, but only if you bet every game.
There isn't an answer. The answers will be as varied as the guys who bet. It is a matter of opinion, and is why football is the number one cash cow for the books. Because everyone has an opinion, and every one knows it all.
Football is no different than the WNBA or Hockey, or soccer. HANDICAPPING it doesn't matter to the bottomline/profit.
Having a plan and an outline no matter what you do is what makes you profittable. Guys could flip a coin in sports gambling, and if they manage their finances the right way they could probably make money. They surely wouldn't lose as much as the so called "pro cappers" who "specialize".
Winning at sports gambling, whatever the sport has nothing to do with handicapping.