I think the best way is to look through a deck of tarot cards. This site is decent. https://www.trustedtarot.com/card-meanings/ Just go through, look at the illustrations, and think about what message it feels like the images are conveying. After you have an idea in your head, compare it to the explanation they've got there. You can go with the meaning you've thought of, replace it with an interpretation you read somewhere, or combine a bunch. They're just cards without inherent meaning, so just do whatever feels right. If you feel like you're getting some value out of that, then maybe buy a deck.

Grab a writer raise or other deck that the art speaks to you and go card by card researching and making your own journal regarding correspondances. Then just start doing em for yourself and others, keep a journal with the readings you do and check back for accuracy. Also doing a daily single card draw is useful too, it's a great hobby but dont fall into the deck collection rabbit hole it's a money sink