It is important to choose a deck that you really like. You will have it for a long time and you have to live with it; people rarely give away their cards, so unless you inherit an unwanted Tarot deck, you wil need to purchase your own.
There are so-called traditions that dictate that you should not buy your own cards, but that they should bought for you as a gift. Do not worry about this – choosing cards is such a personal experience that it would be difficult to rely on someone else to do this for you.
If you have not bought a Tarot deck before, try a twentieth-century one that has numbered cards, such as the Rider Waite deck. The images on the card will stir your memory if you already have some familiarity with the Tarot, or will help you learn the card meaning from scratch.