Basically, the silicone (or other rubber) suction cup is attached to a motor. The suction stimulates the genitals, increasing blood flow towards the clitoris and surrounding tissues, which promotes engorgement and erection.

It's similar to penis pumps that also use a suction sensation to bring blood flow to the penis to enhance erection and appearance.

For many clit pumps, applying some lube on the silicon cup and on the clitoris and/or vulva will help create a better seal between the suction cup and the clitoris/vulva.

As mentioned earlier, some clit and pussy pumps are designed for just arousal. Some are for arousal AND orgasm. And for some people, they may use clit pumps to help produce a larger, more sensitive clitoris or vulva.

1. Start Slowly And Lightly

If you were to go skydiving, you probably would go tandem skydiving first with an instructor versus by yourself — and get some training beforehand to know what to expect.

While using sex toys is not quite like skydiving, the principles hold true that you should start carefully before going straight to 10 in intensity. While there might be some excitement in trying something new, some pumps can be more intense than others so you'll want to get a feel for what you're getting yourself or your partner into. There have been reports of not only the larger pumps causing pain or tissue damage, but also smaller suction toys from being too intense that you may not expect to be problematic, so that's why I'm urging caution here.

2. Test It On Your Arm First

If you want to dip a toe in the water and get a feel for the general sensation, try a lighter setting on your arm first to get a feel for how the device works and what the sensation feels like. While it won't be quite the same as putting it on the clitoris or the vulva, it can help you learn how the device works and how different settings feel before you put it somewhere more sensitive.

3. Use Caution With More Intense Pumps

Some pumps are designed to be stronger — particularly if you're looking to engorge your genitals for a larger look. If you are interested in that, use caution with these larger pumps because if it becomes too strong, you may inadvertently cause tissue damage to your genital area — and that's not fun to recover from.

4. Now you are ready to start work

place the chamber (some call it a suction cup) around the proper area so it seals firmly to the skin. Chamber size matters, since vaginal pumps and clitoral pumps are designed for different parts of the genitals.

It’s time to start the “pussy pumping” and get your blood flowing. Squeeze the bulb until you start to feel suction developing; you’ll want to keep one hand on the chamber the first time or two you squeeze, until you’re sure the seal is tight. Once you see your labia start to swell, you should begin to feel an unusual but arousing sensation in your genital area.

Don’t pump too much; you’re not inflating a bicycle tire! Go slowly, one pump at a time. Once you notice and feel the suction, only squeeze the bulb once or twice more. As you get comfortable using the pussy pump, you may want to leave the chamber in place for a few minutes, 5-10 minutes at the most. If you feel any actual pain, or are ready to remove the chamber, just hit the quick release valve on the pump once and the chamber will come right off. (Some pumps have a second release valve on the chamber itself.) 

You’re now ready to enjoy your newly-sensitive genital area. You may want to relax for a minute or two, however, to let blood flow resume normally. You’ll still be extremely sensitive, but the area will be dry due to the action of the vacuum pump. Using lube may be a good idea when you’re ready to play.

Don’t be afraid to get imaginative when using a pussy pump. Not only can the device get you ready for sex play, it can become a part of it. Watching the process of genital engorgement may be a turn-on for both you and your partner; at the more extreme end, there are BDSM possibilities as well. (We’re not going to list them – as we suggested, get imaginative!)

Your pump should be cleaned thoroughly with soap and water after each use, and stored in a dry, cool place separate from other sex toys. Be sure that the device is waterproof, though, if you plan to submerge it or get any of the electronic components wet.