Summarize the following:
for a banana that is yellow and lightly speckled with small brown or black spots. Some people prefer the firmer yellow-all-over stage; some prefer the softer, sweeter, stronger-flavored yellow-and-brownish stage. If the banana is not ripe, you can leave it on a warm counter for a day or two. If you are in an in-closed area, such as a room, throw it away in a closed bag or closed trashcan, otherwise the banana will fill the room with its odor. Alternatively, you can also save the banana peel to use as compost in your garden.

Summary:
Buy a ripe banana. Get rid of the skin.