What room? What type of surface? And how bad is the mold?
Cleaning mold can be as simple as using a Clorox wipe to a complete tear out of the walls.
For most surface molds on ceilings such as bathrooms, a good cleaning using a bleach and water solution will be fine. Remember however, the bleach will kill most of the mold spores, not all, and bleach has a tendency to remove the color out of the mold spores making them harder to even see. So you must not only clean the surfaces, but create an environment that is less conducive to mold development.
Mold grows because of moisture and food. Food being the painted surfaces or materials that make up the walls or ceilings. Dust, soap scum all are food sources of mold as well. You cannot really control the food source all that well but you can control the moisture. In bathrooms, open windows, or turn on fans. Get the humidity out after a hot shower. Even in the winter. On ceilings where this mold tends to develop faster then everywhere else. Check to see that the ceiling is properly insulated. Cooler ceiling temps allows the moisture to condense faster then on walls. Also no one ever wipes the ceiling down after a shower, they do tend to do this on walls.
If your mold is not in your bathroom, where is it? Mold is a sign something else is wrong that needs to be corrected.