Presuming that this is a sunny site, plan to install a mix of plants. Sow annual rye to prevent erosion while you plant shrubs and perennials. Make pockets in the steep slope and plant some viburnums, forsythia, weigelia, bridle wreath, mock orange--select the shrubs you particularly care for. Plant perennials among the shrubs, again making pockets in the hillside. Use sun-loving sedums, short ground covers to fill the remaining spaces. Sedum acre, for instance, will fill and spread very well.