Ques:

In putting Kirchoff's voltage law one draws a schematic diagram of the circuit and then indicates the current in each leg (a.k.a. branch) of the circuit. For every leg of the circuit how does one know which way to draw the current.

Answer:

If you guess incorrect on the current direction when you solve for the current in that branch of the circuit you get a negative value for the value of the current. A negative rate for a current in a specified direction is simply a current in the opposite direction.