Seems easy. Just hit on 55 percent of your NFL bets and you can make money for the season. No sweat. Read up a little bit, check the Friday injury reports and let nature take its course. If an octopus can pick World Cup games correctly, how hard can it be to pick pro football winners?

But if it was that easy, lots of people would be making a living at it and sports books would be forced out of business in less than a month. Picking pro football games against the spread is part knowledge, part insight, part crap luck. Lots of factors play into it.

There are few secrets in the NFL, and that’s the way the league likes it. Injuries have to be reported, the Internet allows oddsmakers (and bettors) to mine franchises for information. All that results in tight lines that are hard to beat. But there are a few factors that bettors can look at before throwing down their money:

1. BET EARLY. Sportsbooks all try to be the first up with numbers, and the Vegas books and offshores are all trying to get early action. Games for the following week are often posted late Sunday afternoon. Be ready to hit as soon as you find a game that you really line. Make sure your team has not suffered any major injuries. Oddsmakers are good but not perfect; every once in a while they post a line that’s a few points out of whack. If/when they do, jump on it early before betting smooths out the number. Numbers rarely fluctuate more than a few points from late Sunday to game time the following Sunday, but you want those points in your pocket.
2. LIMIT YOUR BETS TO A FEW TEAMS. Knowledge is power, and it’s impossible to know everything about every game. Concentrate on fewer games and hit them harder. For several years I made an annual trip to Vegas and bet on every NFL game on a particular Sunday. The best I ever did was 8-6; the worst was 6-9. For the last few years I’ve limited myself to 3 games each Sunday and bet more, with better results.
3. RUN AWAY FROM DOUBLE-DIGIT FAVORITES (especially on the road). The public loves favorites, and dominant teams draw lots of play. But there is talent on every team, and the margin between winning and losing so narrow, that it makes no sense to give away huge numbers. In 2007 the Patriots went undefeated in the regular season and started 8-0 ATS. But in their final 11 games (including post-season) they were double-digit favorites 10 times, and were 2-9 ATS in those games. Flip the coin over and look at the 2008 Detroit Lions, who were winless (0-16) SU. After going 0-4 ATS to start the year, they covered three of the next four, with all three covers coming on double-digit lines. Detroit, in fact, was 7-1 that season when getting 10 or more points, and 6-0 on the road.