Please read your manufactures instruction manual.
Mineral deposits can clog your steam iron. You can dissolve them by pouring some white vinegar into the water tank and letting it steam for several minutes. After cleaning with the vinegar, iron an old clean cloth. Residue will be deposited on the cloth. Cool the iron and rinse with water or distilled water if your iron calls for distilled water. If you get frequent mineral deposits, it might be because you are using tap water.
If you use spray starch, it will stick to the soleplate of the iron and need cleaning. The best way to clean it is to make a paste of baking soda and water and then brush the soleplate with an old clean tooth brush. If it isn't coming clean, then apply it again and scrub firmly. Cleaning it regularly will prevent the stuck on spray starch rubbing off on clothing when you are ironing.