Learn the trick to perfectly ripe avocados!
You can tell an avocado is ripe by looking at two things: the skin should have turned from a green to a dark brownish-green and it should bounce right back after giving in slightly when you gently squeeze it. If the seed rattles when you shake it, it is because it has pulled away from the flesh because it is too ripe.
Never refrigerate whole unripe avocados since they will never ripen in cold temperature. Instead, place in a cool dark place, preferably in a dark paper bag (trapping the ethylene gas). If you do this with a firm avocado at room temperature, it should take three to six days.
If you need to speed up this process, place another fruit high in ethylene in the paper bag with your avocado, such as an apple, tomato or banana. It will then usually take only one to three days.