You love your new jean jacket but hate that it looks ... well, so new. Creating vintage clothing and accessories is a process that allows a well-constructed, fresh garment to look used and abused. When you fray the cuffs and hems yourself, you can control exactly how much distressing and perfection you wish to leave behind.
Wash and hang dry your denim jacket. If the jacket is new and you want to preserve as much of the indigo hue as possible, toss in a cup of table salt and wash it on cold. If you want a little more discoloration and an "older" look, wash on warm with a cap full of detergent.
Iron the jacket after it dries. Ironing smooths any wrinkles, showing you accurate sleeve and body length.
Mark the sections of the cuffs and hem you want to snip away using the chalk. You won't need to remove more than a half centimeter or so of fabric to achieve the fray effect.
Snip away a small section of the lower edge of one cuff. All you're trying to do is remove the perfect finished edge, not shorten the sleeve or body length. Repeat for the other sleeve, the lower edge of the jacket's body, pocket flaps and collar as desired.
Open the scissors. Scrap the edge of the blade against the newly frayed fabric, causing it to loosen up and look more natural. Stop when you're happy with the results.
Wash the garment once more, removing the remaining chalk and loose threading.
Remember, if you cut below the natural hemline, the fraying will not go beyond that point.