You absolutely have to smell your fruit! If it is ready to be eaten, a sweet scent should emanate. Be careful though, the smell shouldn't be too strong, or it could be spoiled.
A melon is sweeter (and so tastier) when it is heavy. Weigh the fruits before picking one.
You should know that a ripe melon easily comes off the vine, and this can be used as an indicator for a mature fruit.
You can actually judge a melon by its cover! A nice fruit will show around ten stripes. The sharper they are, the better!
Finally, don't stop your choice on a fruit that looks too soft : this is the sign that it isn't really good anymore.
Because we love melon in all its forms, here are some recipes to enjoy a nice and fresh melon!