[julie_m]

Instead of saying "everything flowing in is positive, everything flowing out is negative and they all add up to nothing", I found it easier to take an educated guess on the directions and say that the total current entering (treating everything as positive) is equal to the total current leaving (again treating everything as positive). If anything turns out negative, it just means you guessed the direction wrong in the first place.

The two are mathematically equivalent, of course, but I just found it easier dealing with mostly positive quantities on opposite sides of the = sign.