There is actually a bit of delicateness that one must use in considering choking. Many “official” bdsm people disavow it completely, out of the principle that it cannot be 100% safe and consensual because of the risk of the bottom losing conscious. However, many do still acknowledge that it can be done harmlessly and essentially eliminating that risk, by making sure to use an added margin of safety. I will explain. Ultimately, this is an oft-requested kink, and it would be a shame to completely disregard its arousing potential. (although actually I only do it as a top, it does nothing for me as a bottom, interestingly)
That said, this is something I only do if requested, but it has been requested by many partners.
To do it, simply take your thumb and either a few fingers or the upper part of the palm of your hand, and place it on the two sides of her wind pipe in the middle, so effectively you are squeezing her neck. Then press down, obstructing her flow of breath.
Do not push on the windpipe itself. Most commonly her eyes will roll up and you can see her gasping.
The point about the margin for error is the length of time. Keep it to perhaps 10 seconds at the most. She just needs to feel the sensation of being physically prevented from breathing, and that it could endure, not the actual panic of suffocation, to be aroused. If she gets off on suffocation itself, she will naturally recreate the sensation by trying to breathe multiple times and being unable. Meanwhile she still has enough oxygen and will remain conscious the entire time. You can do it multiple times of course, but give her just as much time in between to breathe. If you follow this protocol, everyone involved in your choking play will have a good time.