i always wash my material before sewing with it i put it in the washer with warm water and little soap
but before i wash it i either serge or sew around the raw edges before washing and have never had a problem with "strings" also that way when i bring new fabric into my sewing room i know that if it has been sewed or serged around the edges it has been washed, after i take it out of the dryer i iron it with spray starch and get a crisp piece of material to work with , sometimes i noticed wrinkles are easier to get out if i dont use steam to iron them ( depends on the material)