Art plays an important role in the overall design of a space. A collection of smaller frames (rather than just one big piece of art) adds texture to a wall and can create a focal point in a room. The pictures below show different ways in which you might arrange your art. Whether you like the more structured arrangements or want something more random, consider a larger grouping than you might otherwise be comfortable with.
A collection of random frame sizes, but structured because they all rest on picture ledges.
The light frames and white mats unify this collection.
A completely random collection in frame size, color and arrangement.
Structured in all ways. The lighting makes this more like an art gallery and provides great indirect lighting in a room.
Arranging by color is a great way to make your collection into a real statement.
And, don't forget that walls aren't always horizontal in nature. Look for other places in your home to create a collection that might be a little different and unexpected.