A large picture or work of art makes more impact if it is placed in a prominent spot by itself. Medium size or smaller art pieces used for wall decoration are more likely to be appreciated if they are grouped together on a wall rather than scattered throughout the room.

Test Your Grouping Before You Decide
Standard decorating practice states that it is much easier to arrange your photos or prints using templates before you make your final decision.
Cut templates of all your photos and pictures from brown Kraft paper. Arrange them on a table or the floor until you have an arrangement that pleases you. Tape them to the wall with removable tape. Live with this a few days and decide if you would like to make any changes before you go forward with your wall decoration plans.
Carefully Choose the Correct Height
When considering wall decoration, location makes a big difference. Don't hang pictures for your height only. Consider the proportions of the wall as well as the surrounding furniture. A general guideline is to hang pictures 6 to 8 inches above the furniture. If the picture is hung too high, it will seem to be disconnected from everything around it. If too low, it will interfere with the use of the furniture and will not be viewed properly.
As with anything else in home decorating, rules are made to be broken, so if you are not happy with a particular location don't be afraid to go against this idea. Sometimes, pictures are meant to be viewed from a seated position. Be sure and check this out with your templates before you make a final decision. At other times, a huge piece of art may look better closer to the ceiling, away from the mantel or sofa. Only you can be the judge of the preferred location for any piece of art.

Wall Art Does Not Have to Be Square
Don't lock yourself into the idea that all pictures must be hung in straight rows. Let the shape of the area guide your wall decoration arrangement. If there is a dormer in the shape of a triangle, or if you have a cathedral ceiling, arrange your templates to fit into that space. All the outside edges do not have to line up in a straight line. If it helps, cut out a large template of a triangle, of the shape of the area you want to decorate. It may be a circle or perhaps a long rectangle. Then arrange your photo templates on this larger template. This will help you visualize your finished arrangement before you hang items on the