There are many different methods to reading tarot cards, just like there are many different opinions and attitudes toward intuition, spirituality and "psychic" work in general.
I like the more modern, no drama, holistic approach. As I see it, any given card has multiple aspects, both positive and negative meanings that are all part of the same card...just like the positive and negative terminals are inseparable parts of the same battery, or the north and south poles are inseparable parts of the same magnet. The card, the reader, and the person getting the reading are all part of the same wholeness of the cosmos...that's the connectivity that allows a reading to be meaningful and useful in the first place. In that frame of reference, which way a card is oriented on the table is relatively unimportant. Often I'll use that contrast of upside down vs right side up cards as a nudge toward one meaning or another, or a gentle spin on the overall pattern in the cards, but not so much as to make a complete change in the card's meaning.
An older, more traditional way is to have one meaning when a card is right side up to the reader and the total opposite meaning when it happens to land upside down to the reader. In this style, orientation on the table means a great deal.
The Ace of Cups is a good example. It is often associated with abundance, creativity, intuition. Turn it upside down, and it can be associated with lack, greed, being confounded or rejected in romance. These meanings have very external, predictive connotations. I like to think of it in terms of the internal world rather things outside ourselves. Even the two different aspects of a cup can be either positive or negative. The card can be either, the reversed card can be either.
Think of the symbolism of a full cup...it can be a sign of abundance..."drink deeply, the cup of life is full"... OR it can hint that we are "full of ourselves", with no room to learn or grow. There is no room for more, no room for new or better.
On the other hand, think of the empty cup, the ace of cups in reverse...
An empty cup can be thought of as lack and emptiness, OR it be understood in the classic Zen terms of "only the empty cup can be filled"...that a place has been made for abundance to enter. There is a place for growth, learning, love and wisdom to be, so that makes it easier for it to come...a very positive, hopeful thing.
Either state of a cup, empty or full, can be positive or negative. Either orientation of a card, normal or reversed, can be either positive or negative too.
Sounds complicated, doesn't it? It does take a little practice to get used to using that kind of complexity. That's why it takes practice and skill to read for other people, just like it takes training and skill to be a good counselor or a good mechanic.
This kind of complexity and inter-relatedness also shows why the cards are just a tool. It isn't the hammer, nails and wood that build a house, it is the carpenter. It isn't the cards, or crystals or tea leaves that give the reading...it is the human mind, spirit and intuition. Anyone can learn to read cards or listen to their intuition, just like anyone can learn to hammer a nail. Some people have more of a talent for doing it well, but anyone can do it.
Wishing you a day of abundance, and drinking deeply from the cup of life.