The line is going to move toward the team that is being bet on the most. You can see up to date trends on online sportsbooks. For the most part, public money is usually on the favorite. If there is heavy money the spread should increase. Many times they don't change too drastically. On the other hand if the public is betting hard on an underdog, the line would be worse approaching game time. On some occasions there will be opposite line movement. This can mean that large bets were made the opposite way, which is sometimes a good sign for the team losing points due to the movement. In my experiences with those, it's best to stay away unless you have a strong feeling. It's good practice to observe the line movements and use them to your advantage. The linemakers are good at what they do, get as much value as you can.
Hope that helps
GL
