KidsandCars.org offered some safety tips for parents to avoid hot-car tragedies:

• Avoid leaving children alone in or around cars. It is not acceptable to leave children in cars for any time at all, even if you are only running into a store to grab a few things.
• “Look Before You Lock.” Form a habit of continually opening the back door to check the back seat before leaving the car to make sure a child isn’t left behind.

• Create reminders. For example, keep a stuffed animal in the child’s car seat. When the child is occupying the car seat, take the stuffed animal out and place it in the passenger seat as a visual reminder.

  Read more here.