Search around http://bogglesworldesl.com there is a travel English section that may have some worksheets and activities ready to go.
It's not hard really.
- Drill/Go over the vocab.
- Practice with a map (use a worksheet)
- Give them a new map with destinations and go.
- Follow up with asking for directions from real points in your town to other places
If they are intermediate they shouldn't really have too much trouble with the asking for and understanding vocabulary.
Mark (above post) has good ideas. I would get them to concentrate on the speaking and listening. Perhaps get a local map, pick some landmarks and have them role play asking for directions from A-B.
Have some mystery destinations - perhaps you give them a starting point then give them directions, either spoken or written, and see how many end up at the same point, or the place you intended them to.
lesson plans 
Linear Mode
