Each president should have in his (someday her) mind what his goals are in various areas of foreign and domestic policy. Then, on a daily basis, he must apply those goals to things that come up each day.
For example, let us say that Pres. Obama has as a goal to keep Pakistan on our side in the War on Terror and the conflict in Afghanistan. Each day, he must decide what to do based on that goal. So when the Wikileaks thing happens and the Pakistanis see what our diplomats are saying about them, the President has to react. He has to try to determine what he can do that will make the Pakistanis most likely to remain on our side and then he must do that.
So, on a daily basis, the president must see what is happening and try to react in such a way as to achieve his goals.