The ranks of horse betting enthusiasts and the community of baseball betting aficionados are part of the larger family of people who bet on sports on an appreciably consistent basis. All of them could give you lessons about betting online, lessons that online gambling experts have studied and absorbed for the past few decades.
1) Betting lines are for generating action, not necessarily determining the true merits of each team
This is the part about betting lines that the casual fan does not understand… and which online gambling experts don't want the general public to appreciate. For example, when looking at a bodog review, you regularly see point spreads with half a point involved. The whole notion of a "seven-and-a-half-point spread" is designed to get action on both sides of that number. If people think that a game will be decided by no more than one touchdown, they'll take the underdog plus the points. If people think the game will be decided by two scores, they'll take the favorite minus the points. The key insight here is that the betting action is being divided by the artificial construct of the score. It's not just an assessment of the two teams.
2) Gambling lines are the product not just of the present moment, but of history
You had to wonder why Virginia Tech was only a 10-point favorite over Pittsburgh last week in college football, and why USC was only an 8.5-point choice over Stanford. It's not that oddsmakers knew everything there was to know about these teams in the middle of September. The key point to make is that they knew the histories of Virginia Tech and the USC-Stanford rivalry. Oddsmakers knew that Virginia Tech struggles in September. They also knew that Stanford had won four of the last five games against USC and had regularly played the Trojans close over the past half-decade.
3) Luck is still a factor – there are no such things as luck-proof bets… that's why it's called "gambling."
Oddsmakers don't want you to think that luck plays a large role in deciding bets. This is part of why point spreads are used to generate betting action on both sides of a line. As long as the line is set in a tantalizingly attractive place, debate and interest in a game will be perpetuated until kickoff time. Once the game starts, though, you never know if a late garbage touchdown will create a backdoor cover. That's just the way sports are… and can be. There's no solution to a twist of fortune such as that.