You should also watch lines during games. For example, a favored team can start the game at -250, then if they're down by a few points in the third, their line will be at something like -125. Depending on the match-up, this might be very good value because the team might still actually be heavily favored, despite being down at the moment. The opposite is also true.
It's also good to look at stats. If a team's line has changed significantly, but you can see that it's because of an statistical aberration, then it's a good bet. I talked about that during Toronto's game against Orlando. They were down by 8 at half, and it KILLED their line. I looked at stats, and they were shooting 20% from the floor, while Orlando shoot something like 45%. And only down by 8. Since it is extremely unlikely that Orlando will shot a lot higher than that for the second half, and Toronto almost certainly will improve their %, it was good to bet on a Toronto come back. They ended up losing the game on a missed FT at the very end. But it was a good bet, and those payoff over time.