Cards are by deck.
Tarot deck has generally 78 to 79 cards depending on the reader. Some readers will add an extra 'unknown' card.
The way a tarot reading works depends on whether all of the cards are used and how the reader uses them. There is no set way to read cards. There is a set meaning to the cards based on the symbology of each card. The combination of the cards and the interpretation of the spread has first to do with the question being asked. The mediumship of the reader is going to depend on their skill, experience, and ability to read pictures and numbers, and the really excellent readers, which are few in number, will have extensive knowledge of the tarot. Most use books and are amateurs, even tough they say they have been at it for a while.
Just because a person says they are experienced doesn't mean they know what they are doing with the cards.
I got a tarot reading the other day and the advisor said she had been reading for over 30 years but didn't know what the 4 of pentacles meant! Got it completely wrong. I chortled and won't wont call her again.
The spreads are whatever. Basic spread is like this:
shuffle cards. Cut deck into three stacks from left to right using the left hand.
Left Middle Right stacks
Left stack is past
Middle is present
Right is Future.
This is a basic spread.
then there are many other types of spreads depending on the reader. There is one that is called the astrological spread. It is not helpful if the reader has little background in astrology though. There are some who will say they know astrology when they know nothing about it and therefore the astrological tarot spread is not accurate either.
If you can get an answer with 3 cards, that's the answer. It won't be any different with more cards or a different spread, just more complicated and murky.
I'm really confused as to how the cards work. I understand that the reader pick the cards at random...but isn't that just by chance?