1. Identify the spaces you want to fill. Art should be more or less in scale with the space it hangs in, which means you'll want large pieces for large spaces (over the mantle, if you have one) and smaller pieces for smaller spaces (between the twin windows, for example).
 
2. Decide on a color scheme if you haven't already.

3.Decide on a mood or identify the one you've already created for the room. Is your living room a formal Victorian parlor? Or an informal space with beach mats and beanbag chairs on the floor for kids to sprawl around on?

4. Look for pieces that complement your theme. For a living room, it's best to avoid anything too controversial - landscapes and black-and-white photographs are fine, but erotica and dead animals are out, unless you really want to make a statement (or put some things away when your mother-in-law comes over).

5. Consider incorporating several themes or categories - hang them wall by wall. You might, for example, have one wall with vintage sepia-toned photos and another with small desert landscapes.

6. Frame the pieces well if they're paper, using archival-quality mats and sealing the backs. It's a good idea to match frames, especially for similar categories - for example, cream mats with narrow black wood frames for all the black-and-white photographs; double mats and gold leaf frames for your set of Italian lithographs.

7. Make it a point to check your pieces once in a while. Light changes during the year, so something that's fine in December may find itself in direct sun come June - and a piece that's fine one year may take on moisture damage the next year if the backing comes loose.

Tips

• Especially if you live in earthquake country, make sure to choose appropriate hangers (according to the makeup of your walls and the weight of your pieces).
  
  
• Red is the canary in the coal mine for art - it's the color that goes first when a piece is getting too much light. If you notice changes, move the piece.