After finishing a project or work day where exposed to fiberglass, remove your clothes in an area where the particles won't shake off onto other fabrics. It's probably not the best time to give your spouse or partner a tight bear hug either. Remove clothing and keep it separate from other laundry or furnishing -- for example, don't drape it on a chair or across the bed or the fibers may spread. It may work best to just toss the clothing into an empty washing machine and plan on washing it by itself rather than mixing the pieces with others.
Many companies that work with fiberglass products publish statements in their required Material Handling Data Sheets (MSDS) suggesting that clothing be washed separately and in warm water until fibers are removed. However, no specific guidelines for soaps or detergents and methods are given. Forums suggest using boar's hair or other rough-bristled brushes to slough off some of the fibers before washing. Others mention applying strips of tape or other adhesives to pull the particles out before putting the clothes in the machine. Most sources do add a step after washing that includes thoroughly washing and rinsing the washing machine itself after finishing a load of clothing.
How clean and fiberglass-free you can get your clothes also depends on how much you were immersed in disrupted fiberglass. Many projects involve working with the composite form, which is tight and has little fiber shedding, so a normal wash cycle, or two or more, may be enough to ready your clothes for the next project.