Now is the time to go to the library. You want to thumb through the magazines, the gardening books, the landscaping books, and anything else you see there that has pictures of gardens. Guaranteed, you will spend more time with each picture in the beginning than you will after a few references. After a while, you will find yourself taking longer with some pictures, pausing, or even doing the ahhh. What this exercise is for is to get a feel for the different designs and types of gardens. Ideally you will find a general style you like. It may even be a mix of styles.
Keep a planning notebook and write down things that catch your eye. An inexpensive spiral notebook is good. Or, use a 3-ring notebook, some notebook paper, some photo copy paper, and a few sheet protectors to gather anything clipped or copied. In this notebook, also start writing descriptions of your yard's lay out, soil type by area, type and amount of sun by area, natural moisture conditions by area. In the notebook, start writing what you envision in terms of gardening labor: amount of time, type of tasks you do or do not like, seasonal differences in terms of your availablility, etc... And, start writing out what you would like your yard to do for you and give you (i.e. edibles, ornamentals, play areas, entertainment areas, hide the garbage cans, privacy concerns, security concerns, traveling paths, etc....) Don't forget to write down the names of books/magazines and enough information to be able to find again the "cool" things you come across. If you see plants you like, write down their common and ideally their latin name.
Ultimately, you will probably want a plant encyclopedia that has some type of a picture or drawing, something about the conditions the plants like, something about thier growing habits, and ideally any notes about specialized care or maintenance. The book I like is the Sunset Western Garden book. Even if you don't live in the west, there is enough description about their climatic zone classifications that it is probably useful throughout most of the country. A used book is cheaper and just about as good as a new one; actually I like some of the older editions better than the newer editions.
In terms of what grows best in your area, how big does it grow, and when does it bloom - I like to do a lot of neighborhood driving. If "everyone" for miles around all have a particular plant or shrub ranging in age from 1 to 100 years - you know it is hardy in your area even if the books say it is questionable. If the books and tags say a plant grows 5'-8' and yet all of the older houses have 20'-30' monsters of the same plant in their yards, you know that not only is the plant hardy for your area but also to disreguard the maximum plant size reference on the label and in the books. Don't forget to look at wooded and open areas for ideas among the native and naturally growing.
For year 'round green, think evergreen shrubs.