When you see a picture for sale at a flea market or thrift store, if you don't care for the picture, look beyond to the frame. Frames can be expensive when new, and the thrift store is the perfect place to find cheap frames with personality. Don't worry if you can't find matching ones. An eclectic mix is trendy and adds fun to the room. Replace the picture with an enlargement of one of your own photos. Old calendars are also a great place to look for frameable pictures. You can create a collage effect on your wall with a mixture of sizes and frame types. Frames are also easily painted to revive them or change their look.
One of the cheapest ways to get fabric for curtains, or other cloth decorating, is bed sheets—either thrifted or purchased on sale. You'll rarely, if ever, find new fabric for sale at these prices. One fun idea is to use patterned sheets as wallpaper for a small area such as a border. Soak the fabric with liquid starch and smooth it onto the wall. The starch will dry clear, it stays in place very well and it's easy to remove later by applying hot water or steam. If you like, you can paint and apply an inexpensive piece of molding where the border meets the rest of the wall.
A fun and trendy idea is to combine rich fabrics with rough-textured, more inexpensive ones. For example, buy a little silk from the remnants table at the fabric store to make one side of a pillow, and use burlap for the other side.
Houseplants can quickly bring warmth and life to a room. Get creative with potting containers. A pretty bowl or shallow vase from the thrift store can find new life as a pot for plants. By asking friends for cuttings from their plants, you can add greenery to your rooms for practically nothing. Be careful to keep your plants in healthy shape; a sickly, yellowing houseplant doesn't add anything pleasing to the look of a room.
Mirrors are a well-known idea for enlarging the look of a small space. Keep them sparkling clean.
Tuck as much clutter as you can away out of sight. Use one or two objects that have special meaning to you on an end table rather than a jumble of random things or messy stacks of magazines. Pare down what is visible to create a cleaner, more restful appearance. This tactic will make it easier to clean your small apartment as well.