If your full-size bed is too big for your bedroom, consider removing the frame. Head boards and foot boards can take up additional space that you don't have to spare. Set up your bed with the box spring and mattress only; use decorative pillows at the head of your bed to give the illusion of a headboard. With your bed on the ground, your wall will appear heightened and make your room appear more spacious than it is.
If it's within your budget, and/or expertise, create a loft space for your bed. This will double the functional space of your bedroom. You'll have a loft space to sleep in, as well as the entire floor area of your room for waking activities. You'll have storage space for clothing and accessories, room for a television, stereo and computer, as well as additional space for studying, socializing and relaxing. This solution is especially helpful for college students and young adults who need to maximize the use of a small amount of space.
If your full-size bed is too big for your room, consider clearing out any additional furniture other than your bed. You'll need alternatives to traditional storage like dressers, desks and bedside tables; purchase plastic containers that slide underneath your bed for clothes and accessories. Purchase a lap desk for a portable work surface, and downsize your desktop computer to a laptop. Instead of using a television that requires a stand, mount a flat screen. Install shelves for books, plants, pictures and knickknacks; hang hooks for scarves, purses, belts and hats. Use tall, narrow lamps that stand on their own in the corner, rather than lamps that need to rest on a table.
If no amount of maneuvering and downsizing can help you get your full-size bed in your room, consider alternative bed solutions. Purchase a day bed, futon or convertible for your room; this will allow you to have space to work and socialize during the day, and a comfortable space to sleep during the evening.