Well, I've never really summoned a fairy before, but they seem to be attracted to me for some odd reason. Well, I would say astral project to their realm and find one that seems to be attracted to the most. Learn their name and when you come back to your body, remember the information.
It may not work the first few times, but with practice it may. Go to a peaceful place and try chanting: "Oh (insert name here), my new fairy friend, come to me and always be around." You can adjust the chant to fit your needs, but as said before, you must keep him or her happy if you want to keep your new found friend.