I could have sworn I replied to this thread, but I will do it again.
Based on the info I have gathered from members of this forum, sales reps at boutique jeans shops and designer stores... this is the best way to wash jeans.
First and foremost empty all the pockets. Turn the jeans inside out and only wash like colors/washes together. Meaning, you want to wash dark jeans w/dark jeans and light jeans w/light jeans. Also do not wash more than 5 pairs at a time. Your best option is washing by hand, my washing machine has a "hand wash" option so I elected to use that. Use mild detergent, I prefer TIDE (but thats preference). Following the washing AIR-DRY your jeans. DO NOT PUT THEM IN THE DRYER. It will only shrink the jeans or mishape them. I air dry mine outside on a sunny day. Good luck