Well it is not very easy. I personally can't do it because even I don't know enough. I do know the basics which are:
(1)you have to know the "TRUE NAME" of the spirit you want to summon, the only way to be sure is to get it from the spirit themselves.
(2)you have to know the definition of it's "TRUE NAME", basically you have to know what kind of spirit you are summoning like the "personality, self image, and nature" of the spirit.
(3)you have to have the power to summon it, like fishing; once you hook the fish you have to reel it in, if your line is weak it can get away, or else you have a fish that is stronger than you and angry you hooked it to begin with.
(4)if you have the strength to pull up a spirit, you may still have to pay tribute of some kind to get anything out of it.
BE SURE YOUR READY BEFORE YOU TRY ANY FORM OF MAGICK, EVER, AT ALL.