First, consider the herbs that you use in cooking or in teas and whether you want to dry the herbs for later use or will just be using them fresh. This will help you to determine varieties and amounts to plant. Then consider the site. If you want a formal herb bed, a vigorous herb garden will require a full-sun site. If you have a lot of shade, it may make the most sense to include herbs among your plantings that get the most sun. Many herbs, such as mint, can become invasive (to put it mildly). Unless you are committed to keeping it in bounds, plants in the mint family and other invasive herbs should be planted where they have boundaries. I have mine in containers that I winter over. Penn State’s Department of Horticulture has a helpful directory of herbs at http://horticulture.psu.edu/cms/vegcrops/node/1