hmmmm...I can't really remember the most I've made, but when I read at the New Age store, I often made $200.00 a night--cash. I would read for a few hours and could only charge $20.00 a reading per store rules--($30.00 actually, but $10.00 went to the store)--and I use to work about 4 hours each time, giving 30 minute readings. During the months from about May to the first part of November, $200.00 a night wasn't so unusual tbh.
As for what method I used--*shrugs* I just took in a few various tarot decks, allowing the customer to choose which deck I should use. I never read with spreads, I just threw cards till I felt it was done. I never had the customer tell me outright what their question was--just to think of it as they shuffled. Then about 1/2 way through the reading-but before it was done, I'd ask if the reading made any sense to them and rarely did they say no--that it did definitely answer their question and then I'd continue on.
I am also an empath and psychic-medium, so often would get some extra information through out the reading, which I would share as well, of course--so it wasn't always just a card reading with me. I was the only psychic-medium, empath reader there at the time, so I did get quite popular when reading in the store.
Keep in mind that the cost of a reading will vary depending upon where you live. $30.00 for a 30 minute reading, was actually a decent price and lower then most other places. However, I have a friend who lives in New York City, who got $300.00 per reading/client and it was also only a 30 minute reading at the same time I was reading in the store. And the card reader I go to was in the same state as I was in, but she was/is expensive and earns on average $500.00 a day cash and over $100,000.00 a year from reading the cards.
My hub would retire if I could pull that off!