Fruit – How to tell if a cantaloupe is ripe

Depends on if you'll buy for instant consumption or for storage.

If you want to eat/prepare them right away, you want an avocado that feels soft on the inside, when pressing them they will cede and have that soft feeling ripe avocado has. It shouldn't cede very much though, as those are past their prime. The very good ones even smell in a nice avocadoey way a bit (or maybe that's just my insanity.)

If you want to prepare them later, you want firm ones that cede only a tiny little bit (the rock hard ones mostly never ripen in my experience,) you then store them in a porous bag (the typical brown paper bag or a newspaper) to let them ripe. To speed up the ripening, you can add an apple to the bag.

See also this related question

You can let it ripe at room temperature.

If you want to slow down the ripening process, put it in the fridge, although this will affect the mango negatively. If you want to speed up the process, put it in a bag with a banana.

When the mango is ready to eat, it will be slightly soft if you press it and you can smell the mango flesh through the peel. The green colour will not totally disappear.