Absolutist thinking is a vicious falsehood, creates only confusion.
There are three basic styles of oneiromancy, just as there are three different fields of dream.
There is the theurgic, where through contemplation of divinity and adoration of the presences of the God/Goddess, your dreams begin to take on the nature of that divine wisdom.
Then there is the hermetic, which is through an immersion in language and meaning and philosophy, your dreams begin to manifest more and more clarity in their symbolism. Even potentially developing a lot of the “universal” archetypes.
And the path of the hermit, the tendency for “mad” men and women to manifest profound visions while being immersed in their instincts and strong emotions. This tradition tends to be very good at predicting physical and metaphysical shifts. So yes, the mad hermit of the village was given some respect, because very often if he or she started saying, “Everyone is going to get sick!”, they were right.
Which of these paths of oneiromancy would work best for you is totally individual, and they all, if developed to full maturity, can reveal the same depth of insight.
How do you do dream divination for another? You would have to talk with them and get yourself immersed in their world? To a degree, yes, or you can from experience of your own dream divination see how their symbols connect to yours. The connection is usually there for a reason, and interpret it that way. This still gives you a reading.
The way you develop your oneiromancy is to make a practice each day of paying close attention to something you want insight about. Not analyzing it, that gets in the way. But say you want to be able to predict the weather. Each day for about three weeks, go outside for about thirty minutes and just watch the weather. Feel it, don’t think about it, just let yourself experience it fully. This opens your dream mind to insights about the weather. Then you will find that you start to dream of rain at night, and the next day it will rain. This can be done with anything you would want to track. It doesn’t make it rain. It just tells you in your dreams that it’s going to rain. It’s like the weather telling you what it’s going to do in advance.
I suspect oneiromancy is not something that would suit everyone. Some people wouldn’t want to let more of the world in their head.
Is every dream a divination in that it tells you how things are going if left unaltered? Every dream is a revelation, yes. It’s a divination when it is communication between you and the world. But yes, when you are awake you can build your own set of symbols in your head to dream about, and by that, open yourself to deeper insights about whatever you have focused your attention on. That is oneiromancy in a nut shell.
Your thoughts are welcome. Be well friends.