Let your jeans get dirty for as long as possible.
First wash: dry clean.
Following washes: soak your jeans for about an hour in water with a little Woolite black added, rinse, roll in a terrycloth towel and hang up to dry.
Soak your jeans for about an hour in water with Woolite black added, don’t scrub.
Rinse, wring and hang up to let the water drain
Machine wash at 30°C (90°F), delicate cycle, no spin cycle, with Woolite black.
Let your jeans get dirty as long as possible, go swimming in the ocean wearing your jeans, rub them with dry sand and repeat several times. Rinse in fresh (not salt) water and let dry in the sun.