The best way to learn safe choking technique is in a BJJ gym where they take safety seriously. You'll get choked a lot, which will give you the necessary empathy to avoid harming your partner.

If you ignore this advice and choke without understanding anatomy or the danger of applying a man's strength to a fragile woman's neck, you risk permanently harming or killing her. Even leaving marks is legally risky. Prisoners who harm women and children are pariahs and prey in US prisons. They get tortured, extorted and stabbed.

The larynx is fragile cartilage. If you've ever been hit there and suddenly had to hoarsely suck wind, you know how suddenly an emergency tracheotomy can become imperative. Most people don't know how to perform one. Brain damage begins after 5-10 minutes without air, death at 15.

I prefer not to impede the airway at all. A blood choke is much safer, as long as it is brief and mild. (A strong blood choke causes unconciousness in a handful of seconds; brain damage begins in 30 seconds.)

To practice a blood choke, simply squeeze the sides of your neck with the fingers and thumb of one hand. You will feel increased blood pressure. This is harmless in small doses.

In my opinion, that is enough. If she needs more sadism, apply it to a durable area like her ass. The neck contains all the body's vertical conduits and none of the padding. There are safer places to play rough. For example, her nipples need toughening for the baby...

I searched TheRedPill subreddit for "choke" and found some comments addressing safety. There are many there who know more about choking than I do, but none explained the technical aspects with sufficient detail and gravity.