Well, as people have already told here... just do what feels natural and comfortable to you. You don't have to make a petition or anything if it feels awkward or if it takes something away from your reading experience. Then again, if it's something that feels comfortable to you and helps you focus, by all means do it. People do have their personal Tarot rituals that work for them.
Unfortunately, so many people impose their personal Tarot preferences and rituals upon you, stating you must and mustn't do this or that (like do a prayer, wrap your cards in silk, pick them with your left hand, wear black clothes while reading, wear white clothes while reading, never charge for readings, you must always charge for readings, etc.) There's nothing wrong with Tarot rituals and habits, but only pick the ones you personally like! The truth is, from what I've read on this forum, people use their cards in very different ways, and they all get accurate readings.
It appears some people need a sense of ritual (such as a dedicated reading place, candles, incense, meditation) to set them in the mood, while others treat the cards in a very practical and matter-of-fact manner. It's up to your personality.
That being said, I have a habit of blessing my new decks with a simple ritual. I do it because it helps me sort of "initiate" my deck, to turn it from a mere pile of cardboard and ink into something personal. For me, this is a "must do" because I can't work with a deck that hasn't been blessed... but I'd never go around telling other people they'd have to do it as well.
