If I were to buy a tarot

get what you like what speaks to you. you can wait for someone to gift you a deck, but how long is that gonna take. and what if its a deck you do not like? I have been given a deck and bought my own. As for books go to bookzz.org and type in tarot in their search bar, if there are any there it will come up. I am pretty sure there are. I got 21 ways to read the tarot from there. It may have a 3rd z. not sure. Good luck!

I know nothing about tarot but try booking a class in tarot reading

Buy the one you are most attracted too. This will usually be the right deck for you.

If the exk you have is based rpund the RWS deck, there re some very good YouTube channels on he topic. I would suggest Tarot Oracle for a start, and he Sacred Texts web site lso has some very good tarot information.

Spread out your sources a little for broader learning and more ideas.

You should go on to Aeclectic, they have sample pics of hundreds and hundreds of decks there. They also have reviews of several books.

Check out Tarot dot com too, there are fewer decks there but all the cards are shown :)

When you're learning the cards then pick one that you are most comfortable with and you're most drawn to, as mentioned already by everyone else the Rider Waite deck is the most obvious choice. Its simple, clear and a classic, all the symbolisms in the artworks will make it incredibly easy to learn the meanings of the card and every card is able to tell a story. Even if you're not particularly drawn to it for performing readings, if you have the extra cash to spend I would still recommend it for learning purposes and another deck for doing readings with when you've learnt the cards. As someone with a few years of tarot reading under their belt, the Rider Waite deck is still my absolute favourite and go to deck.
A few other common beginner decks are;
-Morgan Greer tarot deck, I believe its heavily based off of the Rider deck.
-Hanson Robert deck,
-Sharmen Caselli tarot deck.

Regarding the superstition of someone else buying the deck for you, I had a more experience friend who taught me how to read the tarot, and I've sat in while she did readings for other people; what she would do was let the querent choose from selected decks for their reading. I think allowing the querent to select the deck brings the focus back on to the querent (as they're the one with the question/s). Just a thought.
Obviously if you only have one or two decks, its not very viable.