Know the look you want. It helps to have at least a basic idea of your preferred style and maintenance level. Do you prefer formal gardens or a wilder, more free-form look? Do you want plants that thrive under benign neglect, or are you willing to take on specimens that need a lot of care and attention? Will you need paths, pavers or other hardscaping? How do you prefer to water? A little direction will help your pro fine-tune your options. At the same time, allow room for creativity — your landscaper's imagination and expertise are the reason you hired him or her. Be open to feedback and suggestion. And don't automatically nix plants you think you dislike; you may find that they gain a whole new appeal as part of the right overall scheme.