learn all you need to know.  In general, be careful of organs, joints
(including vertebrae), and veins.  Avoid applying heavy pressure to the
kneecap, back of the knee, the abdomen and the front of the neck.  There is
a right direction (toward the heart) and a wrong direction to apply
pressure.  (Veins have valves that act to prevent the back flow of blood
returning to the heart.  You don't want to blow those valves!)  Read the
`toward.heart' file in the archive (see question 5.1.2) if you are
interested in the discussion of why certain massage techniques do not go
towards the heart.  Similarly, the abdomen should be massaged in a
clockwise direction because of the way the intestines are laid out.
        Obviously avoid broken bones, acute inflammations, etc. and use
caution if the recipient has a medical problem, including infections.
Information and advice about massaging bruises, and dealing with chronic
pain, is available in the archive.  Cancer and plebitis have been mentioned
as conditions incompatible with massage.
        Beyond that, you're responsible for getting your own expert
therapeutic, medical, legal, etc. advice :-)
        The `warning' file in the archive contains some of the more dire
warnings posted to the newsgroup.  The `toward.heart' file in the archive
contains some more information about the direction in which to apply
pressure.