Choose an interior wall and paint a country scene. You may have to remove any existing wallpaper and glue before you paint. You can paint a small mural on one of your walls or create a border around a center molding strip with a country scene such as a barn and horse, a stream flowing through a meadow, silhouettes of horses or horse-drawn carriages or any other scene that you prefer. Ready-made murals and decals are also available that you can apply to the wall.
Check out an RV accessory catalog or a country decoration store and pick out curtains with your favorite country themes. Country-style curtains are often gingham or plaid or may be embroidered with a country element.
Consider painting any molding with a faux grain finish or removing the existing molding and replacing it with a rustic wood-grain style. Rustic wood grain is a quintessentially country look and you can find this material at most home and garden stores or building supply stores.