NFL betting - tips?

[MrGo]

I have bet on football before but have no real strategy. I follow the season pretty closely and I know what teams are good to bet on and what not.

My question is how do you guys bet on the games? Straight up? Parlay? Other? I have been told by others that parlay's are a waste of money and shouldn't be attempted.

I'm looking for a smart way to bet on games; not a gambling fun way.

Thanks