Blueberries are one of the fruits that once it is picked, it will not ripen anymore. They are either sweet and ripe, or yuck!
We have found that when you get your berries home, DO NOT WASH them. Place them on a single layer cookie sheet and freeze. Then take the berries and place in ziplock bags or containers and place in freezer. You can then remove the amount needed for muffins, cereal, or just munching. Wash them when you unthaw. That's all there is to it!
Here are a few good links that will assist you with keeping your blueberries in the refrigerator, freezing the berries, and some yummy recipes.