Sun visors do more than block the sun these days, with the added weight of GPS units and CD cases weighing them down and eventually causing them to droop. This looseness is a fairly simple issue and you can usually fix it in a matter of minutes with basic hand tools.
Sun visors are generally flat pieces of fiberboard wrapped in vinyl, plastic, or other material. Visors are attached to the interior roof of your vehicle at two mounting points. One is a fixed mount where the visor snaps in and out of place and the other is a swivel mount that allows the movement when you raise or lower the visor or move it to shade the side window. The mounts are nearly always the culprits of a droopy sun visor.
The swivel mount is the most common cause of sun visor sag because it experiences the most movement and wear and tear. First, tighten all screws that secure the mount itself to the roof. Next, check closely for a smaller screw near where the sun visor connects to the swivel mount. This screw, if present, directly adjusts the tightness of the sun visor's up and down movement and commonly loosens with time and use. Turn the screw clockwise to tighten it and check the visor's movement. You don't want it extremely tight or it will be too difficult to move the visor. Once you've adjusted the screw, you just may have resolved the sagging issue. The screw will tend to loosen as you use the visor, so a more permanent fix involves removing the screw entirely and coating it with thread sealer and reinstalling it. Then simply adjust it again for proper tightness.
The fixed mount is simpler than the swivel mount and usually does not contribute significantly to a drooping visor, but there are a few areas you can check to be certain. Just as with the swivel mount, begin by tightening all screws that attach the fixed mount to the roof. The only other consideration is where the visor itself snaps in and out place. Check to make sure that it fits securely in the fixed mount when it's snapped into place. If it doesn't, you can replace the tips of the mounting bar from the visor or add small rubber caps to them to increase the thickness, thus giving a tighter fit with the mount.
If the sun visor is damaged or beyond repair, replace it. Depending on your vehicle, this may be a very simple job or a highly demanding one. However, the principle is always the same: remove the mounts from the interior of the roof, disconnect all electrical wires, and install the new visor. Visors are generally not found at auto parts stores, so you will have to be source one from a salvage yard or a dealer.
