Large Amount of Wall Space
Make sure you are installing the shelves in your living room on a large amount of wall space. This is so that the shelves and the items placed on the shelves don't run up against each other, crowd other pieces of furniture or window frames in a living room. There should ideally be equal space around these shelves on all sides so that they, and what is stored on them, stand alone as their own piece of decoration. Also plan for what you are going to place on these shelves in advance, so that you know how much room to leave around the shelf so that these items don't encroach on anything else.
Shelves that you are installing on the living room wall yourself should be level but can be tiered at different heights, creating a different sight lines along the wall, allowing you to decorate with different objects at different levels. This is especially useful on a very large empty wall in a living room where a lot of open space needs to be filled. By creating different tiers of shelves on the wall, negative space is effectively wiped out in different areas, allowing the living room to look more fully decorated.
Place Shelves Around Furniture
Stand up shelves in living rooms also make good bookends for furniture in a variety of different ways. Shelves can be placed around a couch against the living room wall, towering over it on either side, or around the television or entertainment center, allowing you to put records, DVDs and other pieces of equipment on each shelf as necessary. Shelves of different heights are also useful in these scenarios as the room shouldn't be dominated by these storage spaces only complimented by them. Best of all, they are not attached to wall or the floor, so these shelves can easily be moved when you reconfigure the room.
Hanging art on the wall of a living room is pretty common and placing a smaller shelf right beneath the piece on the wall compliments this, as it will give people a number of things to look at in a row. Whether you start on the objects on the shelves and work your way up to the art on the wall or vice versa, neither the wall art nor the shelf and it's contents will appear isolated, making the living room look sparse and shabby. So use shelves to compliment other objects you may have on your wall, in many other rooms of the house.