Summarize:

If you need to decide which works of art to display, try to come up with a theme. Look through your collection, think about your style, and decide what kind of tone you want to achieve. Figure out whether you prefer uniformity or more eclectic looks, and decide what would look best in your space.  Suppose you have lot of works in one genre, such as portraits or landscapes, and want a more uniform look. You could create an arrangement of works solely in that genre and use frames with consistent sizes and colors. If you like visual puns and storytelling, look for objects in your collection that relate to each other in clever or interesting ways. For instance, a pair of portraits might seem to glance at each other as if they’re laughing at the same joke. If you want a vibrant, dynamic look, choose a wide array of colors and artistic styles. Mix up abstract works with representational landscapes, portraits, and still lifes. Include as mediums as you have in your collection, such as paintings, drawings, prints, and photographs. For a more minimalist, chic look, look for artworks that fit a particular color scheme. You could arrange black and white photographs, charcoal drawings, and black and white paintings. Black and white frames would reinforce your arrangement’s uniformity. If you're going for a cohesive arrangement but still want a pop of color, you could go for a monochromatic look. For example, display works together that are all predominantly blue. While frames shouldn’t overwhelm artworks, you can use them to complement your arrangement’s theme. Mix up your frames to create a dynamic look, or use frames with consistent sizes and colors to impart unity.  For example, suppose you want to cluster several similar works, but don’t want your arrangement to be static. Use frames with different sizes and materials to add variety to your collection.  If you want to unify a broad range of mediums, colors, and sizes, use all black frames, wood frames, or frames with equal thicknesses.
Look for themes within your collection. Combine contrasting colors and forms for an energetic arrangement. Display black and white or monochromatic works for a subtle look. Use frames to create uniformity or variety.