Cantaloupe is actually one of the
easier melons to select, because of its
thin skin.
Watermelon,
honeydew,
canary melon, etc do possess a thin skin, but then have a
firm layer underneath it that is mostly inedible. But the cantaloupe can be eaten nearly right up to the
skin.
A good cantaloupe is a light tawny tan all over. It may have minute bits of black or brown marbling from growing, but no large patches. Any marbling should look like the melon has been splatter painted, and only be in a small area. The cantaloupe should be slightly firm all over but not have any hard spots nor mushy areas. Remember what you are feeling immediately beneath the skin is what you are going to eat. If it feels like it would hurt to bite, or if it feels slimy, you don't want to eat it. Once you have one that feels good, smell it. You should be able to smell a sweet aroma through the skin, just slightly. It will be the strongest, usually, at the 'dent' where the stem attached. It will not be a very strong smell, but if you can't smell it the fruit is probably just under-ripe. This is fine if you don't want to eat the cantaloupe for three or four days, but if you want one for breakfast tomorrow, get one that already smells ripe.
Slightly green cantaloupes will ripen up on the shelf pretty happily, and cantaloupes store in the fridge quite well, but watch them; if they get just slightly over-ripe they start to leak juice out of their very thin skin, making a sticky mess. It's best to put them in a fruit/veggie cooler, or if you must put them on a rack put them on something firm. A cantaloupe can "impale" itself on a rack, its own weight pushing the bars into the fruit, causing the aforementioned sticky mess.
To eat your now-excellent cantaloupe, if it was on the counter, put in the fridge overnight. If it was in the fridge, go you. Cantaloupe, according to most people, is far superior icy cold, tasting sweeter, less mealy and slimy, and far more refreshing. Cut in half, scoop out seeds and strings with a spoon (or cut into quarters and just cut off the string/seed part with a knife. You lose a little flesh, but in the end it's less tedious). Serve cubed, in halves or quarters (for the latter two, use a grapefruit spoon if you leave the skin on, a fork and knife if you don't.) Cantaloupe mixes very well with honeydew and canary melon. Some people like it with watermelon, many do not like the texture mix. It also mixes with strawberries or blueberries fairly well. But most standard 'fruit salad' fruits do not go well with cantaloupe, the textures and chemical composition do funny things to the other fruits and leave weird tastes and textures in any added fruit.
Enjoy your perfect cantaloupe.