The number one rule is to check each garment label to determine the fabric content so you can set the correct temperature. Most irons have gauges with fabrics listed on them so you can set the iron accordingly. In general, synthetics should be ironed at low, wool and silk at medium, and cotton and linen at high. Iron a garment on a too-hot setting and it can become shiny or, worse, burn or melt.
Work in up-and-down strokes, following the line of the fabric. Circular or zigzag strokes can stretch or otherwise damage fabric.
With knits, press and lift the iron (rather than stroking it) to avoid stretching the fibers.
To set a crease, use a burst of steam. For fabrics that require low temperatures, set the steam on low and hold the iron two to three inches away from the fabric. For those requiring higher temperatures, set the steam on high and hold the iron six to eight inches away.
To ensure that a press sets, let the garment cool on the ironing board or a hanger for five minutes. If handled while warm, the garment can wrinkle.
With delicate fabrics or intricate details, such as pin tucks, gathers, or ruffles, don't bother pressing―just hang the pieces up and steam them. If a material won't respond to steam, take the garment to the dry cleaner.