If you were to pick a deck of cards 30 years ago, you would have had a handful to choose from and it would not be an arduous chore like it is now.  Or you would still be in diapers   and maybe hitting puberty

The first thing you have to do is ask yourself what you want the deck to do.  Do you want it to give you the answers from the meanings you will have to memorize or look up in the accompanying book?  Do you want the deck to inspire you and to promote your psychic awareness through the imagery of the cards and a few keyword?  Are you a believer in angels, power animals, North American Indian/Asian/Qabalah etc. traditions?  

Do you want to psycho-analyze yourself and try and figure out what makes you tick at the present time? Do you want a certain deck because people are discussing it on a forum or in a blog?

Once you have answered some of those questions you should get a piece of paper and write down 6 things you want the deck to give you as far as accessibility to answers.  This way you will weed out many decks on the market.

After you decide that you can read reviews on the Internet about the various card systems.  You can usually see several pics belonging to decks as well.  Many websites offer free computer generated readings which will give you some idea of what they mean in certain spots.  Don’t forget that it is someone else’s opinion of someone’s else artistic & writing talents.    Unless the review is completely unbiased then only consider it slighlty.  I have read horrible reviews about cards/books only to find out that I felt differently than the person writing the review.  So be cautious on that one.

Ok now ask yourself how much time are you going to devote to learning this new deck you are about to purchase?   Even if you have a natural skill in reading card it will not happen overnight and can take many years to fully master. The acquired skill requires a lot of practice.  And some people just never get the knack of it.

Assuming that you are not just going to collect cards & that you will actually use them, you then need to jump right on in - buy the cards and begin.