Glue glass craft marbles or stones around the edges of the mirror to create a pretty, shiny border. These stones are usually found in the floral department of craft stores and come in many colors. Clear and flat marbles will add elegance to the mirror without going overboard. Use a hot glue gun to apply the marbles to the mirror, using whatever design you like.
Paint designs on the mirror. Use a paint brush and enamel paints to create flowers, an ivy border, polka dots or swirls around the edges of the mirror or toward the center. Even if you don't feel like you're up for painting a masterpiece, you can purchase stencils to make the job a little less intimidating.
Stick clings on the mirror. Clings are like stickers that adhere to glass and can be removed if needed. They can be made of gel material or vinyl and come in many different designs and colors. Clings are a good option if you don't want a permanent decoration on your mirror. The clings can look elegant, funky or modern depending on what type of cling you choose.