For direction, you have to think about the cutter moving in relation to the workpiece.

On a moving gantry machine (i.e. typical router), Y+ the gantry moves away from you, and X+ the spindle moves to the right.
On a moving table machine (i.e. typical mill), Y+ the table moves towards you, and X+ the table moves to the left.

Z is easier to remember, as it's simply whatever way moves the cutter vertically away from the work, but that may mean lifting the spindle, or dropping the table.