I've said it before and I'll say it again - BORAX!
This stuff is great. It's a natural mineral cleaner that you can use on any fabric including wool and silk. It helps to get out greasy marks and I've found it particularly good for drawing dirt out of wool, like round cuffs on jumpers/cardigans.
Just add it to your washing water and dissolve along with your washing detergent. You can put it in washing machines or when you handwash. I find it best to soak the item for a bit, say, half an hour to get the best results then was as ususual.
You can even use it to cut grease when you do your dishes or in with your starch to help give linens a glossy finish. It is the best stuff I've ever come across as it is so versatile.
Another useful tip - to get blood out, soak in cold water and salt. Works a treat.