Place avocados in a paper bag with a banana or apple
Keep the bag at room temperature
Fold the bag closed loosely
Check the avocados daily
Add more ripe fruit to speed up ripening
Use a warm spot in the kitchen, away from direct sunlight
Wrap avocados in newspaper if no paper bag is available
If you need them very fast, bake them briefly in foil at low heat, then let them cool
Avoid refrigerating unripe avocados
Once ripe, move them to the refrigerator to slow further ripening