1. Off-center a small piece of art near a small piece of furniture, such as a reading chair or console. Avoid hanging in the middle of a wall, isolated and looking smaller than it really is.
2. Off-center a small piece of art to a sofa or chaise. Balance is created from the sofa decor pillows / throws so the artwork becomes part of an entire grouping.
3. Group small pieces of art together on one wall, often referred to as a gallery wall, instead of spreading them around the room, creating a more impressive design impact.
4. Buy a series or a set of artworks that the artist intended to hang together as one piece (i.e. a multi-panel artwork like a diptych or triptych) or that coordinates nicely with each other. They can fill a wall like option 3, but with a more uniform look, creating a 'series.'
Or don't hang at all...try this instead:
Display a small piece of art that can stand upright on its own and place on a shelf, a desk—or even your kitchen counter. Miniature works, art smaller than 6 inches, are great 'fillers' for tabletop decorating as it can be hard to find a small wall to hang them. They create a cozy look and will add warmth and intimacy to any space.
A vintage-styled, metal easel is another option for tabletop that will look great for giving your small / framed artwork height. Tabletop easels are able to adjust to various sizes and can go on your fireplace mantle, credenza, and other places you may decorate.
Pro Tip: place underneath the artwork / easel one or two neutral-colored, hard-bound books without the jacket covers, showing off the linen book cloth and embossed titles on the book spine.
See various tabletop options in my studio photo (mine come from Ballard Designs and Pottery Barn).