One of the most important things to remember is that the Tarot is easiest and usually best used as a personal psychological tool for yourself and for others. The cards have only what power and capability that you have put into them. You must be willing to spend time to study your deck and its uses for hours at a time. Treat your deck as any tool that you would use for a long time that can be fragile, protect it from the extremes of weather and temperature, humidity and being battered about. That said, remember that a deck is useful and valuable, but is not indispensable.
Most decks come with a tiny little booklet of supposed definitions. These definitions were generally written by the publishing house and not the deck's author/artist. In almost every case, this is a virtually useless piece of reading and should be discarded.
To learn your deck you should sit down with it and spend time looking at each card's illustration, symbolism and the emotion you feel when looking at the card. Also look to see if there seems to be a continuing 'story' being shown thru the deck as you look at it. Most decks have such a story running through the imagery, with the same figures progressing along a path in a frame of perspective. Again, this is not true of all decks. For example, the Morgan deck has no order nor story - it is designed with a controlled level of chaos in mind and flows fine when used within its own context, but is distinct from most decks.
If the symbolism on the deck seems a bit too plain or doesn't really stand out to you when you look at the majority of the cards, then the deck is probably not for you. Decks are designed with particular people in mind and not everyone can work the same decks. For a personal example, the Mythic deck, based on classic Greek mythology, flows easily to me, while a Voyager seems too cluttered to me with its collages. The Hanson-Roberts is a beautiful deck of story-tale art and pleasant, but Thoth strikes me as harsh and the symbology cruel and often painful. There are decks that consist merely of concepts in geometry, decks that are pornographic collections and decks that are in black and white instead of color. Find a deck that suits you best, take your time - your may go thru many decks before finding one that works for you, and may own several that are dependent on your personal moods at the time. Make sure you are comfortable with a deck before you try to take what it is telling you seriously.
Remember - only you can tell what you think a card will mean, even with a good artists explanation, the end judge and interpreter will be you. Only with a level of personal confidence in your understanding of the meanings will you get reliable results with the cards.
~ from Maat's Book of Shadows