When you introduce a spread, pay attention to what the cards look like together, who is facing what, etc. Is a card looking off into nothing? Pull another card. If a dark card appears, I will pull additional cards to dig to the root of the issue. So much of tarot is connecting with your intuition, and this is a place where a formula is constricting rather than useful. With that said, there are some spreads that I have found to be effective jumping-off points when starting a reading.
