1/4 Cup white vinegar to the last rinse cycle of your wash, or if you have a center cup in your washing machine for fabric softener, add the vinegar to that at the start of your wash.
Only use white vinegar,as cider vinegar may stain clothes.
I've been making and using my homemade laundry soap and this fabric softener for nearly a year now. I'll never go back to commercial brands again. I have even dried clothes that I had left overnight in the dryer a second time, to remove wrinkles, with no static.