Tack wooden door or wall molding to a wall to form a display shelf. Make a simple wall hanging from a drapery sample, embroidered piece, tea towel or small rug and hang from a stained dowel. Create your own accessory with dried or silk flowers. You can dry the flowers yourself. Also try using some interesting weeds from the countryside.
Plants are always attractive and nice for filling empty spaces.
Use decorative pillows. They can be inexpensive, functional and attractive. Use books to add color, texture and design to an area. Candles can be simple but decorative. Frame a fabric.