If you want a good avocado, you have to plan ahead. Most of the Hass avocados sold in grocery stores are underripe, with green skin and rock-hard flesh—nowhere near ready to eat. So say you want to buy an avocado that will be ready to eat in two days, or three days, or one day: What characteristics should you look for? This is why we made the avocado-choosing primer above.
Keep in mind that you have some control over how quickly an avocado will ripen: If you want it to ripen as quickly as possible, keep it in a closed paper bag at room temperature. If you want it to ripen more slowly, keep it in the fridge. If you want it to ripen at a Goldilocks pace, keep it uncovered at room temperature.