This tip is the most simple but also the hardest for those with kids I find. Laundry tip number eight is only wash what is actually dirty. Sounds easy right? Not so when you have kiddo's who dump everything in to the laundry basket dirty or not.
Every night as I tuck my kids into bed I take a look at the top of their laundry baskets. Believe it or not my daughter who is three has a pretty good sense of what is dirty and I rarely pull anything out of her basket. My five year old son on the other hand changes clothing at least twice a day on a whim and puts it all in the laundry even if it is clean and was worn for an hour. The top of his basket gets weeded out almost daily. If I didn't he alone would generate two more laods of laundry a week. Ummm not gonna happen here mister.
As adults we usually to do not get our clothing very dirty so I find it unnecessary to wash a pair of pants every time I wear them. Also washing them every time you wear them wears out the fabric pre-maturely. Certainly intimates and socks are a one wear to one wash. Use your judgment you know if something is dirty. If you are washing something just because you or someone else wore it and it is not actually dirty you are wasting three things: water, electricity and TIME.