"Turn right at the blue house" may seem perfectly clear to you, but what if your guest sees the color as green, or is distracted by the pink mailbox on the other side of the street? Augmenting your written instructions with photographs will take care of any confusion.
Start by determining a few key landmarks along the route, as well as the tricky twists and turns where someone might go astray. Then take a drive and photograph those locations.
Make a set of instructions by affixing the photos sequentially to a long strip of paper, with the directions as captions below.
Color copy the original as many times as you need. Then fold the strips, accordion-style.