To smooth fibres after washing, there are three major steps: moist, stretch, and dry. Steam is the best way to moisten fabric because fine steam can go deep into the fibres to make them soft and flexible again. Once the moistened fabric is stretched flat by the bottom of the iron, it must be dried immediately and the right level of temperature is very important.

Tips
Shirts and blouses – steam as needed. Iron first the inside, then the outside of the collar. After doing that, do the shoulder areas and the upper part of the back. The cuffs are next, follow by the sleeves. Move on to the back of the shirt, finishing up with the front panels and the button row, moving the tip of the steam iron under and around the buttons.
Linen Linen is notoriously difficult to iron. You get the best and the quickest results if you use a hot steam iron while the fabric is still damp from the wash. Don’t over-iron-the garment should be ever-so-slightly damp when you are finished. Iron dark linens inside out.
Cottons and denims: These are hard-wearing fabrics can almost always be ironed at high temperature using steam on stubborn spots. If the garment is dark, iron inside out to avoid shine.
Trousers – Pull the pockets inside out and iron them first, followed by the zipper placket and waistband. Slip the waistband around the narrow end of the board and iron the upper part of the trousers. Fold each leg, matching up inseam and side seam, and iron flat on both sides. An extra burst of steam will help you set neat, sharp front creases in place.