By leading the eye as much as possible to the area you want to emphasize. Of course physically it should also be the widest part of the room, i.e. if your room is 13' X 15' it should be the 15' length you want to lead you to the shorter wall. You could have mirrors on that "far" wall or a grouping of art. The sofas etc should be on the long wall(s) or book shelves or low cabinets, all looking like they are pointing to the end wall.
Add lots of different textures to make it feel interesting!
Do you mean make your room look bigger?
flooring lines should go OUT, not across. ...same with patterns in rugs. ...same with art... take the eye HORIZONTAL and outside whenever possible.