Demons are usually summoned using the techings of GD or those of John Dee. Basically any type of Ceremonial Magic because they deal primarily with Invoking and Evoking. Specilization has its uses.
But if you are going to deal with the things then not only do you fully have to commit to the teachings and learning curve of the style you choose. You have to remember that demons will act all nice to your face but once your back is turned they'll rip out your spine and use it as a skipping rope.
That said there are ways to enhance summoning like blood sacrifice (although I don't condone killing of anything especially in ritual), Fornication stuff like that. So go forth and be Mary.