Decoration does need not be a costly affair, if you can use your design skill creatively. With so many options available your decorating targets shall be achieved under what you are willing to spend.
Try to decide about the style and color which will be as a base of your decorating plan.
Try also to think outside the box and add a color that brings out light and adds brilliance to the room. Area rugs and pillows should be used to add a character to any room in the house. Decorating the wall with wall painting, tapestry should be considers. Adding Good art work will never hurt and most of them are not expensive.
If you have bedroom furniture then you can also add replace the old antique cabinet hardware with cool new style knobs of brass or any other finishes.