Let's first remove the term demon, it is just not a reliable term to make. A demon is just a spirit which has been categorised by someone or a group of people as being anathema to their viewpoint in life.
You can make a deal or pact with any type of spirit. If we look at literature surrounding this it never involves selling your soul, usually an offering, sometimes carrying out a certain task in their name, worshipping them, or telling others of their power so that they may seek them out and revere them.
If you don't have fine tuned inner senses doing any magic involving spirits is utterly pointless, particularly evocation and pact making. First develop enough ability to commune with spirits, then call upon the certain spirit or ask for a spirit for the purpose you want fulfilling, this can be done in thousands of different ways, simply lighting a candle and praying could do the trick. Then await for the response, after this evocation may be plausible.