Dion Fortune (born Violet Firth) was one of the great esoteric teachers of the twentieth century, and a true priestess of the Western way. I've returned to her works again and again over many years, and I believe I have dreamed of her. One of the most refreshing things about her writing is that she brings pithy common sense to the most complex and abstruse matters.
Anyone embarking on the study of Tarot would do well to listen to the simple and helpful counsel Dion Fortune offers in Practical Occultism in Daily Life, first published in the 1930s.
Here are some of her key points (the subtitles are mine):
Start out with a new deck and get to know the cards intimately
"To use the Tarot properly... requires a very great deal of preparation, and the preparation does not consist merely in a knowledge of the significance of the cards, but in getting in touch with the forces behind the cards... Obtain a new pack of Tarot cards, for a used one will be too full of other people's magnetism to be reliable, and carry them on the person, and sleep with them under the pillow, and handle them and ponder upon the meaning of the pictures in the light of what the book of instructions has to say about them until the significance of each picture is realized. It does not matter greatly which pack is used.
Test your trial divination three times
Having got in touch with one's chosen pack, the next thing is to lay out a divination according to whatever system is chosen...and note down the results obtained and the position in which the cards fell. Repeat the process a second time, and a third time, upon each occasion keeping accurate notes of the fall of the cards, and, of course, thoroughly shuffling the cards between each lay-out. If certain cards keep on coming up, and especially if they come up in approximately the same positions, or even if cards of the same type predominate through the three divinations, it may safely be concluded that the system is working satisfactorily, and a divination may be made on the basis of the recurring cards. But if the three divinations bear no resemblance to each other; if even the balance of the four suits does not remain constant for at least two out of the three, and if none of the Greater Trumps turn up more than once, then it must be concluded that the Tarot is not working for the diviner, and the divination should be abandoned.
Trust spontaneous impressions and learn by trial and error
Divination is a thing that cannot be learnt out of books, but builds up gradually as a system of associated ideas in the mind of the operator. Moreover, one varies very much in one's capacity for divination; upon one occasion one may be absolutely inspired...at another time, one may have to spell out the meaning of the lay-out with reference to the book for almost every card. It will always be found that it is useless to force a divination; if the interpretation does not leap spontaneously to the mind it is unlikely to contain much insight.
The image of the 4 of Pentacles is from a recently-produced "Dion Fortune Tarot" that was not designed by her but claims to be based on her principles.