Succubi are female demons who take the form of beautiful women and invade the dreams of men. According to folklore, they feast on men's bodily fluids and take their life force along the way. Needless to say, succubi are scary. However, if someone wants to summon a succubus, a little precautionary folklore isn't going to stop them.
Succubi are often thought of as very sensual demons, and rituals can be used to play into that aspect of their nature. Setting the mood with candles, incense and the like puts the summoner in the right head space, which is almost always a great first step.
Tenderly anoint the body with oils while imagining a succubus to draw the demon in. After that, just start moving while thinking about intercourse. It can feel silly at first, but apparently spirits like a little tease. After all that, it's a good idea to ask the succubus for a nocturnal visit, then go to sleep and dream of her - making sure not to finish beforehand.
Protection is of the utmost importance when summoning a succubus. Laying out an insulating circle of white chalk or thread can go a long way in preventing unwanted possessions. Additionally, three to five black candles spaced equidistant around the circle can be used to augment the protective magic.
Once you feel secure, lay inside the circle with your limbs splayed and focus on relaxation and centering. Feel the comfort of the circle, then visualize it becoming a gateway the demon can enter through. If done properly, a manifestation willing to socialize should appear.
Encyclopedia Satanica describes a succubus as a young woman with avian or reptilian features and, possibly, cloven hoofs. Perhaps most disconcerting is that a succubus's private area reportedly feels like a cavern of ice, and their purpose is supposedly to take the seed of young men and return it to incubi, their demonic male analogs.
For people summoning a succubus to hassle an enemy or for some demonic conversations, that's probably not a problem. For those with more adult thoughts on their mind, a succubus may not be the best companion.
Lilith is a figure in Jewish folklore who is believed to have been Adam's first wife. Long story short, things didn't work out, and she gave birth to a ton of kids. Those kids are believed by some to be succubi.
Writing a letter to Lilith and signing it with your full name and a bit of blood may very well convince her to put in a good word for you with one of her daughters. Be earnest and respectful, and when the letter is finished burn it with a candle. Relax, sit with the candle for 30 minutes, and hope Lilith is impressed.