Here I describe the actual methods I use. Yes, it is strict, and needs self-control.

The overview is that the only vehicle for stimulation is to be nipples.

Most details are for males, but parts may be useful for females.

Lie down, naked, on your back - very relaxed. Prepare for a possible ejaculation, eg with a tissue over your penis if you need it.

Stimulate nipples with your fingers, nails, devices etc in a way that works for you. I find that a mixture of gentle stokes and brief intense nail use works.

You should aim to feel blood flowing to the genitals.

Resist spasming - relax. Do NOT contract the genital/anal muscles. Only nipples are used. I find that, after 2 minutes, I get a very powerful erection.

Maintain any erection, and imagine energy flowing from nipples into e.g. you genitals, anus, 3rd eye area - try several. This is very very enjoyable and invigorating. . Continue, as long as it works, you might take a short break from your nipples.

At first, you might be desperate to touch your genitals and cause an orgasm, but you MUST NOT. If a nipplegasm happens, that is fine, enjoy it, but it is not the main aim. You should not even look at your genitals.

Every so often e.g. once a week, month etc, you might do an orgasm by other means, not with nipples.

You can do this nipplegasm work every day or 2, see what works for you. For longer gaps, ensure that you consume enough porn to keep your desire up.