Sometimes, you would have to pique its interest to gain its help. Always answer its questions or you might gain poor service. They will do things out of self-interest. You have to keep slightly amusing events happening for it to hang around. When you need something from it, they will know and do it if they feel like it. Or, you may make the name of the fairy and explain in slightly bored but intrigued tones "I need you for my experiment, the part you can do is what you think is necessary". You won't feel the fairies presence, unless it wants you to. Except, things will occur without explanation and by itself. When you no longer need the fairy as a helper, dismiss it in your mind and this makes things boring for it.
Winged fey love lemon juice. The wingless fey like chocolate. Feyish humans like sweets and chocolate or almost anything they crave, they are summoned by thinking of them and needing one nearby. How the fey eat the offering is through essence eating and how the feyish human eats it is by ingestion and essence sucking. Thus, all you really need is to give them energy and they appreciate it. This is done by thinking it to them. Essence eating and sucking is much like a energy vampire sucking energy. When they finish feeding, they can sometimes leave the food flavorless.
Fairies are time beings. Some humans describe them as being in the fourth dimension. The work done there is able to manipulate the world that humans live in. The time there is much faster than on earth. Thier world is called aerth. When you go there, every minute spent there is 10 years outside of aerth. If one did research there, you would find that life would pass on earth from you and when you were finally done and came back, you would be forgotten. If you were a thief, it would be a perfect hiding place. You would only have to wait a minute before coming back. They would have forgotten you entirely. The fairies can be bought though. So, I wouldn't count them as a force to be trusted. You can create a time gate to pull you there and to make a mental query to it "allow only me to pass through to anywhere I desire and pull me back to whence I left to make no time pass at all since I left to go where I did go through you."
This is what one person did named kevin. This is one who summoned a fey, 'I put out chocolate, said feyly (feh-lye), sounds like lie, and when it came its speakin and it sounds like a mouse sorta. I use tunnel vision, visualizing the area near the squeek. imagined the voice the squeek is, was squeeky then calmly. Then it changed as I could see it. Then said translatio, and what should I see except a white aura and I speak to it. It should speak as I can hear the area and the voice, as it speaks in an understandable lang if lucky. But I wasn't and nearly lost most of the chocolate except that which had a nibble in it. So I asked it for something and I got it, I asked for beuty.'