Two couples want the same Saturday and you lose one going back and forth on email before anyone commits.
Clients check your availability and lock the date with a deposit, reducing the back-and-forth around competing inquiries. You pencil in a date, turn down another client, then the first one ghosts and the day's gone.
Hold the date after the deposit is collected, so the confirmed booking includes money down before you decline another inquiry. Contracts unsigned and the final balance still unpaid the week of the shoot, so you're chasing instead of prepping.
Collect the deposit with the booking, then email a card invoice for the final balance and track its status from the shoot record.