balance of betting on each team, you have to carefully set the line where it reflects what you think is the most probable outcome of the game. In other words, you actually do have to predict what you think will happen. If you don't do that, you'll set a stupid line and the betting will be 90-10 against you, and you'll pay out a lot of money to bettors whose foresight was better than yours. The only way to achieve balanced betting on both teams is to set a line that you think accurately reflects a probable outcome. If you've done your homework, bettors who bet against the line you've set will usually be wrong, and you'll make money off them. If you're not good in assessing teams' strengths and weaknesses, you'll go out of business. Sports books have to be generally prescient to survive.