One of my favorite warmup books has nothing to do with the flute.
It's written in bass clef for the tenor trombone. But the ideas it promotes are universal and translate just as well to flute as they do to trombone. The author, David Vining, emphasizes the importance of body mapping as a means to improve your musicianship. If not for the bass clef notation and occasional mention of the trombone, it would not be apparent exactly which instrument this book is intended for. And this is a good thing.
You should absolutely seek out flute-specific guidance if you want to be a good musician. This could be through private lessons, online sources, or a combination of the two. But if you want to be a great musician, you should also look at other instruments and what you can gain from them.
For example, you can learn all you'll ever need to know about phrasing from listening to a well-training singer. They have the advantage (and challenge) of having to sing lyrics, so it becomes readily apparent when they should breathe and how they should shape each phrase because the most meaningful word will get the emphasis. Our music, not having any lyrics, can be a little mysterious in this regard. Listen to vocalists and notice how they don't breathe in the middle of words. See how they pick a high point in a phrase and give it a little extra attention, perhaps through a change in vibrato or tone color. Add these skills to your own personal toolbox.
The idea that we need to keep our air flowing as we move from note to note is easy to see in string players. A violinist draws his bow across the strings, and while his left hand is changing the notes, the right hand keeps a steady bow speed and thus allows for a steady, supported sound. Just in the same way, flutists have to keep a steady speed of air even as we change notes. A cellist wouldn't stop moving his bow in between each note (unless the music specifically called for that), and neither should we as flutists stop our air. An external representation of a process that's mostly internal for us is a great thing to have.
You can learn from any good musician, regardless of what instrument they play. The fundamentals of phrasing and musicality remain the same. Take a look around you the next time you're in band or orchestra, and see what skills your colleagues have to offer you.