Water is essential to ironing. It relaxes natural fibers allowing for wrinkles to be pressed flat. Without water, a hot iron would simply heat the fabric and have no effect on wrinkles. This is why dry cleaners press shirts slightly damp - the wetness of the fibers allows for a crisp, easy press.
Water should be used in two ways during ironing, both for the same purpose. First, it is used in the form of steam. A properly designed iron only applies steam at the front of the sole plate. This allows for easy control and leaves the entire back portion of the sole plate to dry the steam. When ironing, the first few passes are always used to soften the fabric fibers with steam. Only then can wrinkles be pressed flat.
Second, it is very helpful to spritz additional water onto the fabric with a spray bottle. This further relaxes the fibers for pressing. Spaying water onto shirts can actually be more effective at achieving a crisp press than steam alone and can be used in lieu of steam if one's iron does not produce enough.
We sell a small 3 oz. Spray Bottle here at the Hanger Project that can be used for both polishing one's shoes and for pressing. Try using distilled water to minimize the build-up of minerals on your wardrobe and on the iron.