When choosing a ripe avocado, you want to pay attention to color, appearance, and firmness. A ripe avocado will have a dark green to almost black color on the outside. The appearance of the skin should have a bumpy texture. Avoid any that have dents/sunken spots. Lastly, give the avocado a gentle squeeze. If it gives a little, it's ripe. If it gives too much, it could be overripe. Underripe avocados have no give.