Groundcover or terracing? Junipers always work well, Blue Pacific or Blue Rug, are my choice versus say perennials which may or may not be evergreen. It depends how much time and money you want to put into the project. My house sits down from the street and because I like the green of grass, when there isn't a drought, I decided to terrace a portion of my yard with euonymous and cotoneaster because they spread as easily if not more so then junipers and then planted daylilies, iris, coreposis around them so the beds aren't bare all winter.

Here is a link that might be useful: Propagating Perennials

I would go with groundcover, too, as bullthistle suggested. I know of several people who have steep hills and their periwinkle completely covers it. It is awfully nice. As for landscaping: I know this other person who has a very nice garden on her hill. It is filled with small stones and has just a few large plants, but it makes her whole hill extremely nice. I also have a garden on a hill. I plan to put moss and some groundcover. It is a sandy hill, and partially shaded. I flattened the hill near the top and built a rock wall. and then filled the wall in. I planted shrubs on top of the filled in rock wall.