First and foremost: Communication in SM is essential - talk to your partner about what you do and don't want to do, or have done to you. Be as clear as possible - there is no such thing as too much communication. And even though your partner may know you, they are not a mind reader. You must communicate about your wishes and needs.
You should agree upon a safe word before beginning play. A safe word (or physical motion, like stamping one's foot, for example) is used by any partner to stop the action of the scene immediately. There is no shame in using the safe word - it's there for both of you. Both you and your partner must respect it.
Safety Specific to impact/sensation play Generally, for safety, areas of the body with deeper layers of muscle and fat and flesh are the favored locations to strikr eith with one's hand or with any implement. That means: buttocks, upper thighs, muscular back-shoulder, etc. Avoid any hard strikes on areas near any joints, over vital organs, and on areas were the flesh is inadequate to protect things like blood vessels, nerves, tendons. One should avoid striking these areas: on the lower back over the kidneys, behind the knees, insides of the arms, stomach, head, hands and feet. Also avoid scars left by surgery.
Different toys are best for different parts of the body, and different types of bodies. For example: a heavy wooden paddle is best used on a well-padded ass, a small multi-tasseled leather flogger can be OK for the genitals if used with light to mild force. A larger soft flogger can be used on the ass, the thighs and the back safely, even with stronger blows. A leather paddle is safe on these areas as well. A crop or a cane could be applied to a variety of areas on the body, if it is more lightly applied. Parts of the body such as joints, or places where internal organs are not protected by bones, should not be hit heavily. Avoid hitting areas over bones that aren't protected by layers of tissue, such as the collarbone and the anklebones. When flogging the back heavily, never hit the lower back below the ribcage, where the kidneys are exposed. Also, avoid flogging the spine heavily and directly, as well as the base of the neck, or head.
