Here’s what I do (quoting myself in an older thread):
My initial indicator is always the tendril nearest the melon. If completely dead, I check for a field spot/sugar spots. I also thump the melon and listen (as another grower once explained) for a resonance similar to smartly thumping one’s chest—a sound neither too sharp (under-ripe) nor too dull (over-ripe). Since it lacked a field spot (or noticeable sugar spots; and I have seen them without a field spot) I judged the Orangeglo on the basis of tendrils and sound.
Photo of said “sugar spots” (or what I call “sugar spots”) is at linked post. They often indicate a sweet melon, but are not always present—even in good melons. The tendril is the first sign, though. If the tendril nearest the melon is still alive, it is not ready.
By “field spot” I mean the yellow patch at the bottom of the melon. Generally, the yellower the better. Sometimes, however, the color of the “field spot” is deceptive—and sometimes is is even entirely absent. Depends on the melon and on growing conditions.
Tendrils sometimes die prematurely from insects or diseases. Also, some melons seem to ripen further a few days after the nearest tendril dies. Therefore, I like to use multiple methods to determine ripeness, with the final one—the deciding test—being sound.
You get better with experience. In terms of sounding them, compare the noise made by known green ones with the sound made by ripe/ripening ones in order to train your ears. Also, some melon cultivars are easier to judge than others. Been years since I grew Sugar Baby, but I think that one wasn’t too difficult. The only one I grow these days is Strawberry, and I seldom miss with that one.
Good luck!