Your massage ball can be used directly over clothing or on bare skin. If you use it on bare skin avoid using oil as it makes it too slippery. Use a little body talc instead. You can use light or heavy pressure depending on your needs. The pressure can be applied to a single point or rolled over wider areas.
It depends on how much pressure you apply and what kinds of problems you may have. Any application that directly addresses myofascial (soft-tissue or muscular) problems (such as neuromuscular, deep tissue, trigger-point, or similar therapies) may be painful when treating problem areas; the pain comes not from the work itself but from the tissue pathology. If you have serious or intense pain you should consult your physician or health professional.
Avoid using your massage ball over any recent tissue damage, such as a broken bone, a bruise or wound. Care should be taken with deep work on persons with fragile or brittle bones. Areas of internal organic problems should be avoided. If there is any doubt consult your physician or helath professional.
Your massage ball is made from PVC (it contains no rubber). The PVC contains traces of lemon/citronella oils to give a fresh hygenic small. You can wash your massage ball with warm soapy water and refresh its small by applying a mix of lemon and water.