Pressing not Ironing

Before we get started you should know how to press things correctly. Pressing makes the difference between a garment looking professional and looking like a drunken 5 yr old made it. Often new sewers don't press because they are in a hurry to complete a project, don't fall into this trap! Many new sewers make the mistake of ironing instead of pressing. Most just don't know there is any difference. Remember the construction basics: sew, clip, press. For basic pressing you'll need an ironing board and iron. Later you will need a tailor's ham and either a sleeve roll or sleeve board.

Ironing vs Pressing.

Ironing is to remove wrinkles and is done and a back and forth motion. The goal of pressing is to shape the fabric. Pressing involves putting the iron on a single place, holding it, then lifting and moving.  This is designed to prevent stretching or distortion during construction. Pressing is used to make seams and darts lie flat and round sleeve caps.

How to Press

Pressing should be done with moist heat and not moved until it has dried. If your iron drips when you use the steam settings you can either use a moist press cloth or a spray bottle to dampen your fabric. Seams should be pressed as soon as they are sewn. Pressing pants or sleeves (or any other tube) should be done on a sleeve roll or sleeve board. This should be done by placing the iron firmly on the seam and pressing the seam for approximately 15 seconds.

From the wrong side of the fabric (the side the seams are on) open the seams up and press them open.

 The flip the garment to its right side and press the seam from that side.

And you have a pressed seam that looks like it belongs on a professionally made garment. 

Curved seams will need to be pressed on a tailor's ham.

In general:
Waistline seams should be pressed up
Darts toward the center front or center back
Double pointed darts should be clipped in the middle and pressed towards the center.
Armscye and crotch seams are pressed together towards the interior of the garment and trimmed.