The best way to put a cock ring on?

So we want to use a regular silicon ring to improve the erection. I bought a durex non vibrating silicon ring and another similar one , that seems more stretchy. I read that some go on the base of the penis when others go around the shaft. Also some places say to put a cock ring on the erect penis when others advise you put it on a semi erect or a flaccid one. Please help me to understand what should I do.