Not only do containers look attractive, but they also enlarge your plant palette. Enclose your garden, at least partially, with a fence, wall or trellis. You'll capture and intensify the fragrance of your herbs, and in the process you'll gain privacy, structural interest and vertical planting space. Add water in some form, even if only a tiny fountain or birdbath. It will entice birds and butterflies to your garden, its gentle sounds will add a sense of tranquility to the scene, and the extra moisture in the air will further intensify the scent of the herbs.
Most herbs are fairly low-maintenance, but they still require care and attention.
Decide on a garden size you're sure you can handle comfortably, then reduce it by a third. When it comes time to lay out your garden, the principles are the same as for any other garden. Read some of the many books and magazines devoted to growing and using herbs. Explore some literature in which herbs play a part. Celtic myths, the Bible, Shakespeare's plays, and the mysteries of Ellis Peters are filled with herbal references that could spark ideas for a theme garden.