Everyone is always complaining about how every ritual entails a sacrifice upon success and a consequence upon failure. Well, hold the bitching a minute, I mean come on. It's universal. First law of alchemy; nothing can be gained without an equal or greater sacrifice. Three fold law in wiccanism; do evil it will come back threefold, do good and it will come back threefold, et cetera, et cetera. So now that we have a genuine understanding (assuming whoever is reading this isn't a total dumbass, and is capable of reading and comprehending text written in the English language) let us discuss the ritual at hand.
A lot of people know of rituals involving a chat or a game with Satan, but most of these involve the loss of your soul with no chance of redemption regardless of how your meeting the Prince of Darkness goes. These are the sort of rituals we hear throughout our childhood from friends and read in novellas and internet stories that are simply known to be a part of life. Everyone knows of them, and many have tried them (most to much disappointment). There is a way around the inevitable desecration of your soul involving these types of rituals. There is not, however a way to avoid the potential for this sort of outcome. Just don't be a dumbass. This isn't the sort of thing you do when you're drunk to impress your friends (no need endangering multiple infinitely lasting souls: it probably wouldn't work anyway, Satan doesn't often show up in the company of more than one person unless he's feeling particularly rambunctious; he prefers to have private conversations. Better chance to fuck with your perception of reality that way).
So with all of this being said, (and I'm assuming you're going to go through with this regardless of the chances of death, losing your soul, and God-only-knows-what-else. I mean, it's The Devil for God's sake there are billions of horrid things that could happen) let us get down to brass tacks. There isn't any long, lengthy list of things you'll need to perform this, just a room with a wooden door as the main entrance and a bed, a cross or crucifix (made of silver or wood preferably, silver was what Judas betrayed Jesus for, and wood was what Christ was crucified on. Definitely not made of gold or any other precious metal, save silver as previously mentioned) salt, a pin or knife, five taper candles, and matches (not a lighter). Those are only the required items, and optional items include offerings such as cigarettes or booze, a deck of cards if you fancy a game with Satan, and/or a chair in the room for Satan to take a seat.
Satan never turns down a smoke or a drink. If you don't wish to have any of those items, that's fine. Satan will probably have his own smokes and liquor, and if it's a game you're looking to play he'll have the provisions for anything you wish to play, within reason anyway, and offer to share if you do not have your own. And as for the chair, it is courteous to offer your guest a comfortable seat and he may choose to keep better company if you're a total dick to him.
At night (optimally around midnight on a cloudy night) make a small pentacle of the five candles in front of the wooden door whilst it is open in the room of your choosing containing a bed (the lights should be on in the room for the moment). This pentacle need be just big enough to contain the cross or crucifix, and the point of it should be toward the doorway (be sure that it is far enough back so that when you close the door you won't knock a candle over. It never ceases to amaze me how this has to be explicitly explained. If you knock a burning candle over and burn your house down, Satan will most likely refuse to show up, and rather will be sitting comfortably on his throne, laughing his ass off at your stupidity). If you decided to provide Satan a chair, set it up behind this pentacle facing away from the door. After setting this little display up, circle the pentacle with salt and keep the rest of the salt on your person. Satan isn't a big fan of salt and if things go south it might be good to have.
Invite Satan in. There isn't any specific phrase to be said or anything of that sort, you could say anything from "Satan, my good fellow, come on in," to "Yo Satan, my man! Come chill with me." It is best to hospitable with it, so if I were you I'd say "Satan you are welcome into this room for a chat," or something to that effect. After this is said, wait a moment and place the cross or crucifix in an inverted position relative to you (long end of it facing the door, short end facing you) and light the candles from the point, to left, to right, to bottom left, to bottom right. It is important not to move the candles at all from this point on or disturb the ring of salt. And it is important that if at all possible to light them all using one match. Once all candles are lit, lick your fingers and press the match out with them.
Turn the lights off. Place the spent match within the pentacle of candles. After this, take the pin or knife and prick the middle finger of your left hand. Put a drop of blood in the center of your inverted cross/crucifix. Note that by doing this you are offering yourself to Satan for the remainder of the night. He can do practically whatever he wishes to do with you while you both reside in this room. He cannot have your soul without your say-so though. And chances are he will not try to harm you unless provoked. He would much prefer to make friends with you. Anyway, back to the ritual. Be sure to face the door and close your eyes and focus your mind on your desire to speak with The Devil. For this ritual to be successful, you have to have a true will, a very strong resolve, to speak with El Diablo. After a few moments, open your eyes and blow the candles out. Stand and close the door and turn the lights on. If all has gone well thus far, Satan is in the room with you. He accepted your invitation and entered. As long as the door is closed he cannot leave without you opening the door for him... that is, as long as you are still alive.
Thus if he states that he wishes to leave, it'd be best to oblige. As for where in the room, he'll be seated in the chair if you chose to provide one or reclining on your bed. Turn slowly around after closing the door and as soon as you see him, do not under any circumstances take your eyes off of him. As soon as he sees you, he'll be privy to any information about your personal life. He'll pretty much know every damn thing about you, and then some stuff you probably didn't even know about yourself. He generally appears different to everyone, seeing as how he can look however he wishes. He will most likely choose something appealing to you. An attractive member of the opposite sex (or same sex if you're into that) most likely, or if you aren't particularly inclined to indulge in the lust of the flesh, he'll appear as a clean-cut young man. You will probably notice that regardless of his appearance, his eyes will always be nothing but burning embers in otherwise empty sockets. Greet him politely and offer him a drink or smoke if you have either.
If not, he will probably offer you a cigarette or drink, and have one himself. Once he lights up or swallows his drink, he'll ask why you called him. You will want to give him a straight answer. Don't stutter, and don't hesitate. Don't worry though, after this the formalities will be over with and you can relax a bit. Satan has a sense of humor and will likely be cracking jokes and doing various parlor tricks (fire at the tips of his fingers, turning electrical appliances on/off from a distance, shape-shifting, imitations, etc.) before you know it. Just keep him in your sight at all times, and chat him up. Offering more smokes or drinks may make him stay longer if you have these at your disposal, but he will leave before daybreak regardless. The stakes for any games you play, or the answers to any burning questions you may have will most definitely be sinister. He might cut your thumbs off in return for telling you what really killed the dinosaurs, for instance, or maybe kill a family member for a losing hand at poker (P.S. playing poker with Satan: bad idea. He doesn't lose. Ever. And you will pay the price for a game).
If you ask for the answer to a question such as this, he'll state a price, and you're welcome to turn it down, no strings attached. During the conversation between games or questions he will tell you horrific things in a joking manner (enter the "Your dead aunt sucks cocks in Hell" remarks). Don't mind. Most of it will be lies. If you don't pay for it, he's free to tell you whatever he likes, be it fact or fiction. He will never mention your soul. Bring it up, and he won't turn it down though. Despite this, there is a price for everything. It won't be your soul so long as you don't offer, but there will be a price, rest assured. Don't piss him off, and you'll be fine aside from that. He generally doesn't like being disturbed for no reason though, so if you bring him out, don't just say you wanted some company or some stupid shit. If you ever become uncomfortable, tell him it is his time to leave. He must leave if you do so. Eventually at some time before daylight, he'll say he has business to attend to elsewhere regardless. Open the door for him and close it behind him. Don't exit your room until you've disassembled your pentacle, however. Enjoy. Hope it was worth losing your thumbs to find out how the dinosaurs really died.