When you misguide someone, you lead them the wrong way. You might accidentally misguide a tourist by instructing him to turn left when he should have gone right.
Use the verb misguide when you point someone in the wrong direction, either literally or in a figurative way: "I didn't mean to misguide you when I promised you'd love camping in the desert." Giving bad advice is one way to misguide someone, and giving bad driving directions is another. In the fourteenth century, misguide meant "to go astray," rather than "to lead someone else astray."