For fresh stains the best way is with cold water and peroxide but that generally doesn't work so well on older stains.

For older stains I have found the best way is to soak the garment in cold water and then cover the stain with salt or bicarb soda. Rub it in gently until it resembles a paste & leave it for 30 minutes or so. Then wash on a cold wash. Apparently WD40 spray can also help to lift stains but I haven't tried this.

Blood is one of the hardest substances to remove after it has dried though so it may not come out of your clothes but it may at least not be as prominent. And always use cool/cold water. Hot water will just set the stain further and make it almost impossible to remove.