Try on your Levis to determine the fit and a plan for washing and drying. If the jeans fit snugly, avoid the dryer. If your denim jeans fit loosely at the waist and around the thighs, and have at least 2 inches to spare in length, drying the pants in a machine dryer helps shrink the cotton denim to make for a better fit.
Turn your Levis inside out before washing. Unless you want to purposely age your Levis, turning the pants inside out helps the blue fabric remain brighter for a longer time.
Button the flap, if your Levis have buttons, or zip up the zipper for other Levi jean styles. The washer ages waistbands and pockets -- even those turned in -- when the jean fasteners are left undone, due to the extra pulling and tugging from the washing machine during the wash cycle. Buttons survive the machine agitation better when securely fastened.
Loosely fill the washer tub with your jeans. Wash your new blue jeans alone for the first few times, to prevent the blue dye bleeding onto your other clothing. Select a short cycle wash for lightly soiled jeans, and a longer cycle for Levis with more dirt. A cool water wash and a cool rinse cleans without removing as much of the blue pants dye, compared to a hot wash and warm rinse cycle.
Allow the washer to fill partially with water, then add a detergent designed specifically for dark clothing, if your jeans are deep blue or dyed black. Mix the detergent with the water entering the machine by pouring the liquid or scattering the powder at the point the water releases into the machine. The special detergent gently removes dirt while keeping most of the jean color. Mixing the detergent at the water source dissolves the detergent, reducing the chance of concentrated amounts touching the jeans. Concentrations of detergent increase the chance of removing the fabric dye.
Dry your jeans. Set the dryer for heavy fabrics and add your Levis to the dryer, with the pants still turned inside out. This allows the pockets to dry easily, without removing any color from the pants. Dry only 5 minutes, then hang to complete the drying process. Place the hanger with the jeans in a location with adequate circulation and allow the jeans to dry naturally.
Use a pant hanger and hang the pants, or fold and place in a drawer to store before the next wearing.