Once you have the victim, cradle them in front of you and grab their PFD.  Another great approach is to slide one arm under the shoulder strap and grab the other shoulder strap.  You can still escape quickly if necessary and this leaves a free hand for grabbing a throw line or swimming.  If you are securely attached on your rescue tether, you can hold the victim facing away from you in a great big bear hug if they are not too large in diameter.  Another approach is to simply cross their chest with one arm (like a running back holds a football).  This leaves the other arm free to swim with or grab a throw line.