Whenever I learn about a new modality I get a bit anxious over the contraindications.
So with these cups one of the contraindications is over large blood vessels.
Are there certain areas that you place the cups?
It is probably a precaution rather than a contraindication. Care over large blood vessels but that would probably only be a potential issue in a very small number of people. Areas to avoid placing the cups are the crease of the elbow (cubital fossa) and the back of the knee (popliteal fossa). But pretty much everywhere else should be fine.