to be honest, for this photo, 80% comes from luck

Firstly I wanna shoot wide open, it means shallow depth of field, you need to prefocus, but you don't know which direction it departs, that's the luck part

other than that, I keep shooting (probably more than 200 shots around this single flower) to "increase the chance"

"a lot of times you fail" that's probably the one single truth about photography!