I Love Tarot!
TAROT BASICS - Getting Started
CHOOSING A DECK:
I, Tarot Source, am going to say "Start with a Waite deck." * This still allows choice. The deck was created by A. E. Waite and Pamela Colman Smith, and first published in 1910. Now there are various versions available, all with the same basic illustrations but different design treatments. You can explore some of these at Aeclectic Tarot, and read more about the Waite deck at Tarot Reading - Basic History. The illustrations in Tarot Reading Basics are from an original design Waite deck.
Waite decks have clear symbols, many easily understood without any tarot knowledge. Also, each card has an active scene, unlike decks which show only patterns on some cards. Above all, you can easily transfer Waite knowledge to the vast majority of other decks.
Almost all decks come with a small booklet, often referred to in tarot circles as the LWB - little white book. These give key phrases for each card and usually have a tiny section on a spread or two. These are very small booklets and the information can be rather generic - not relating specifically to the deck bought.
This means you will probably want a book to go with your deck. (See REFERENCE - BOOKS for a few starting suggestions.) There are many tarot books, and there are plenty of deck and book sets.
Do make sure that "Waite" appears in the title of the deck, as a vast number of modern cards are based on the Waite model. This means that you may hear a deck referred to as a "Waite deck" when its cards are very similar, but are not actually the same. Often such decks are called "Waite clones".