A common problem with metal gutters is that they fill with leaves and other debris, preventing water from draining through them properly. A gutter full of leaves in the wintertime can cause problems by trapping snow and ice in place and ruining the wood of the fascia. Cleaning your gutters can prevent these problems.
A leaf scoop is a good tool for removing leaves and debris from metal gutters manually. A pressure washer, however, can be used to blast debris out without the need for climbing and standing on a ladder to clean them. This is a messier option, so you may want to remove solid debris first. If you use a leaf scoop rather than a pressure washer, once you've removed the solid debris use a hose to rinse the gutters clean.
Be sure the downspout is draining properly and that there's nothing stopping the water flow. Leaves can clog this part of your system, too. You can use a hose to try to clean it out or a pressure washer. For serious clogs, a plumbing snake can help break them free. Remove the downspout from the metal gutters for stubborn clogs so you can see more clearly into the tube.