The topic of this post is pacts & their importance, as I've been receiving a great number of communications on the subject recently. Its a greatly misunderstood practice, so I hope that by discussing it here, people will begin to understand some of the mechanics inherent in the process.
What are pacts?
They come in the forms of promises, oaths, bargains, deals, ultimatums, and so forth. Even an act as simple as "God, save me from this crisis and I'll do [X]" is a pact, albeit a hasty one done without a great deal of thought.
What purpose does a pact serve?
What can I get from a pact?
The trick is that the thing you are bargaining for must be in the realm of possibility and within the power of the spirit. If either of those requirements are not met, you will either have a one-sided pact on your hands or nothing (good) will happen. Ineloquently wrought pacts are, very literally, dangerous, but I'll discuss that in a few minutes.
What do I have to give when making a pact?
<<<If the spirit is willing to take that as part of the bargain, BEWARE!>>>
Spirits that are willing to take such a bargain know more than you do about a situation and will use it against you at a later date (don't ask me how I know this...).
Generally, a spirit's not going to be all that interested in your soul, however. Instead, offerings of incense, sexual energy, light, darkness (a bit trickier), food, drink, or other tangible forms of energy that are important to you are enough to win their interest. Blood is something that can be given, though to do so as an offering can be more than a little hinky, so do so cautiously.
Even actions, such as donating money to a charity named after the spirit or one that has a purpose similar to the spirit's function can be powerful motivators.
How do I make a pact?
Before you start looking into making a pact with someone or something, divine, divine, divine. You need to first find out if the spirit'll be willing to work with you, if the thing you're going to ask for is within their power, what it'll cost you to get it, and whether or not the spirit is going to play games with you and try to screw you with the pact.
So firstly, do recon and figure out the specifics.
Secondly, you have to formulate the language and verbiage of the pact. A language that is not your own is great for starting and sealing a pact, but a terrible thing to use when actually creating and executing one. Its a pretty sure bet that the spirit'll understand a foreign language better than you do. The words you use in creating the pact must be specific, direct, and limiting. Do not leave anything you should have control of up to the spirit, and do not, under any circumstances, leave what you're to do for the spirit out of the pact.
The more specific you are, the better, for reasons I'll get to in a moment.
Are pacts dangerous?
In reality, they can be. If poorly executed on your part, the spirit gains power over you that can be used to make your life a living hell or worse. Obviously, not all spirits are inclined to do that to you, but many will just for the sake of gaining the upper hand.
Elves, fae, and dwarves, for example, will generally try to pull the wool over your eyes and get the better end of the deal because its a cultural tradition for them. Its only a good deal to them if they are getting more from you than you're getting from them. Demons, on the other hand (as in the infernal, not land spirits/daemons) are the same way, but they like to get the upper hand so that they can wreak havoc in your life if they don't like you or want/need something you have.
Its also worth noting that pacting with a spirit you don't know well is generally a bad idea. You give that spirit more of a foothold in your realm, so its possible that some ill-natured entities will use that foothold to coerce you into making more pacts with them by making your life more difficult.
Its something to bear in mind.
You're always welcome to seek out my advice on the matter, and I hope this has been illuminating for you.
Best of luck & warm regards.