If you want to learn how to see fairies the fastest way might be to catch them on film.
In July, 1917, Elsie took a photograph of her friend Frances with four fairies. Later Frances captured Elsie on film playing with a gnome. The two girls insisted that they could see fairies often down by the stream by the house and finally got tired of no one believing them, and so took the pictures as proof.
The photographs set off a whirlwind of controversy, with skeptics and believers alike not being able to refute the evidence. Sir Arthur Conan Doyle himself insisted that the pictures could not have been faked, and the girls gave interview upon interview regarding contacting faeries and their ability to see them.
Many years later, as grandmothers, the two girls admitted that they had faked the photographs to get back at adults who insisted that there were no such things as fairies, but continued to perpetuate such beings as Santa Claus. The fairies, they said, were designed after a book, and one of the girls abilities to draw learned as an art student. Remember, it was 1917 when this happened, and using a hat pin to secure paper fairies to the ground was a stroke of genius. Many years later, the controversy and confession was made into a movie; Fairy Tale, A True Story. And it is, by far, one of the best fairy tale stories ever told. If you would like to see the actual photographs, go to http://www.lhup.edu/dsimanek/doyle.htm
As far as how to see fairies in your own backyard, there are several ways. (Remember that the girls perpetuated the lie about the photographs only because they were tired of grown ups not believing that they actually could see the little creatures.)
Some of the best ways have been related to me through friends, some through research, and some from "Old Wives Tales." You'll have to see for yourself which method works best for you.
On midsummer's eve, go into the garden just after dawn when the dew is still wet and set out a sugar cube. Fairies love sugar and other sweets, and will come to dance in the buttercups. You must sit quietly and look past where the fairies come out. Traditionally, midsummer's eve is the only time that fairies can (or choose to) speak the human language, so if you want to talk to them, this time of the year is your best bet.
Any evening at dusk you may go into your garden and weed. The fairies like to live in the bottom of the garden where one does not typically weed, so turn slightly away from them. Garden fairies will come out to watch you and if you are quick you will see them.
Look through the eyes of a cat who is staring quietly into the long grass. Creep up and look through their ears and you'll see what they see. It’s easy to learn how to see faeries, you only need patience, sugar, persistence, and respect.