This tutorial can be used on a variety of different types of clothing, but for this demonstration I will be using a dress that I thrifted!
Step 1: Try on the dress and find how much shorter you want to make the dress and measure that length
Step 2: Take off the dress and use a ruler to mark all the way across the bottom of the dress using some kind of washable marker or chalk, like I did. Also, keep in mind that the dress will need a hem, so add about an inch to the original length.
Step 3: Cut carefully along the line with a pair of sharpened scissors.
Step 4: The original hem on this dress was a regular sewn line about 1/4 of an inch from the bottom of the dress. So in this case, sew a hem 1/4 of an inch above where you cut to prevent fraying.