I wasn't allowed in the kitchen until last year, and my command of French is middling at best, but a lifetime of thrift shopping and being clumsy turned me into a stain removal expert the likes of Heloise. All you need are a few natural ingredients you probably have on hand. Pretreat stains as directed above, then wash with savon de Marseille and cold water- olive oil-based soap is magic on delicate fabrics and greasy stains. Remember, use vinegar and baking soda one at a time, not in tandem!
Our clothes are made from natural fibers, so I don't know if these work on synthetics. If you're wearing synthetic clothing, though, you have bigger problems than stained laundry. All items can be found in Paris in bulk (salt, cornstarch, soap, wine, carbonated water) or fully recyclable packaging (baking soda, vinegar).