Use textured paint / bold color to create a dramatic effect. Highlight the wall using architectural or decorative lights. You could also replace the textured paint with market bought or customized digitally printed wallpaper.
Create a gallery wall displaying collection of art or photographs. It is a great way to showcase your personal style and interests. You may have a collection of art, photographs from your travel or perhaps a collection gifted to you by your parents or grandparents.
Install a statement piece like a large framed-mirror, or tapestry to create a focal point on a wall. These do not cost a bomb, but make quiet a statement. You could also use POP, Bricks, Stone, or Wood to create a customized piece of wall mural.
Choosing from a variety of materials and techniques is great fun, but it is important to do so in context of the specific space / environment, rest of the home, time and budget considerations. That is where we come in!