How do u predict line movement?

[RedeemerKing]

I guess this applies to all sports, but especially football because of the length of time the lines are available. How do you know what the line will do? How do u know to bet it and try to middle it later in the week or just holdoff for an extra half of a point. Is there any science to this? What trends, stats, etc. do u look at in trying to figure this out? Does this apply to all sports?
Any input on this subject would be greatly appreciated!


Thanks