I began reading Tarot 35 years ago. I was taught to look at the card, know a predefined meaning, but put it into context with a set spread. If I needed to bend a meaning to fit, I would do so by my gut.
What? How do I know what my gut means, and how do I know if it’s right? Practice. That is the key to anything. As you work with your cards and expand your interpretations of each card in different situations, you grow as a Tarotist. If your meanings are different from the latest must have Tarot book, so be it. You read your cards. The author reads hers/his/its cards as they see fit.
As you learn, you will (hopefully) exchange ideas with other readers and learn new things. You will probably read a few books, articles and blog posts. It’s okay to not know everything. Don’t beat yourself up when you learn something new, because you haven’t been doing it. What you don’t know is not applicable to your current readings. Once you know something, apply it if it works for you.
Consistency is also important. After you are accustomed to a technique, ritual or practice, use it, unless it no longer feels right. Tarot reading is an individual art, and no one can tell you how to read your cards. If you look at a lot of online groups and message boards, you will see that not everyone agrees. In fact, some people can get out right hostile when they don’t concur with another reader. There are different schools of thought and even symbolic systems. You find what fits with you and evolve from there. Just be faithful to your own practices as long as they are working for you.