For those who plan on betting with real money, you should develop a routine
For example, this is usually my weekly approach to betting on games
1) Covers.com - I usually skim over the spreads
2) Check trends (I usually only do this for division games)
3) Point differential betting system: I have an excel sheet that projects a score between any 2 opponents (http://www.sports-betting-insights.com/NFL-Betting-System.html)
4) Walterfootball.com - Picks: I read his writeups because he watches every game and gives pretty good info. He is biased though. A lot of people hate on him but he does have a lot of knowledge since he does nothing but watch football
5) Therxforum - noz introduced me to this site last year when there was a guy MistaFlava who was on a HEATER. I mean picking like 70% and he was very smart and had good writeups. Now I have a few people on that site that I like to follow up on before I make picks.
6) Outside research: In order to win, you have to do research, read, do more research, do more reading, more research, more readins and so on. The more knowledgeable you are on a game the better chance you have of hitting it.
7) If a game seems like its too good to be true, find out WHY instead of jumping on it right away. These are called traps. Perfect example would be Denver -7.5 at Dallas last week. San Diego -5.5 @ Oakland. This week the trap seems to be Indy -2 @ SD. Vegas is not stupid and they have won 4 out of 5 weeks this year. And won BIG.
8) Always check injury before games.
9) Never let emotion or your biased opinion affect your decision to wager on a game. If you are a Philly fan, bet on Dallas if they are playing Oakland if that is what the winning side looks like. The money you win or lose has nothing to do with rivalries. This is a business. Now, having said that I personally never bet against the Lions but I treat them the same as I do every other team in the league when I do bet on them.
The most important singe piece of advise is this: ***DEVELOP A MONEY MANAGEMENT SYSTEM*** Lack of this is what ruins people. Understand that Vegas has no limit on losing or winning but you should. Some people suggest you should never wager 1/12 of your bankroll on a single team. You will go through losing streaks and winning streaks. Having a plan to completely control your money is key. If your trying to make money over time you are planning on making it over the course of a season and that means you cant win all your money in one week, but you can definitely lose it in one week. If you want to bet half your life on one game this post doesn't apply to you.
Good luck to everybody and just giving my 2 cents for those of you who are considering wagering for real money!