There are still people who underestimate the importance of dreams in Magick so I am going to explain why are dreams really important and how to atually work with them.
Consciousness versus unconsciousness
There are many ways how to define this but let's just say that your personal reality is split into what you are conscious about and what you are not conscious about. The amount of influence of your conscious and unconscious parts on your life is about 50:50, and of course consciousness also affects your unconsciousness and vice versa.
Unconsciousness does a sort of a compensation work for your daily life, it's a very cleverly designed process, but sometimes the fragment of our psyche (usually traumatic one) gets supressed from the conscious and so transfers into your un-c where it becomes more or less autonomous. This then turns into neurosis and affects your conscious life (sorry I am simplifying so much).
Another work of unconsciousness is to gather and analyze details we are not normally aware of, it can be the most subtle mixture of various physical senses up to the metaphysical perception (e.g. telepathy). This allows our consciousness to be much less occupied with seemingly unimportant details but it can also inform us back if one or more of these "unimportant" details sum up to some important event or a piece of information, but for that to happen, it also needs a communication channel, a link between conscious and unconscious.
What are dreams
Dreams are the most direct communication channel between consciousness and unconsciousness. With their help un-c can actually give us its experience of our waking lives but from its perspective. Due to the nature of dreams we split them into following categories:
A compensating dream tries to inform us of something we are omitting even while it is important, it shows us what we should be focused on or what we are forgetting.
A reducting dream is a sort of a healing mechanism. It repeats a bad experience over and over again in a symbolic form till we get used to it and it doesn't appear as horrifying anymore.
Prospective dream can give us insight into the future. It is not a prophetic dream as in a prophetic dream all details would have to match with the real future event but it can still give us enough details to spawn a lot of curiosity.
Reactive dream is like a reductive dream, except in the case of reductive dream understanding the symbology and interpretation of the dream automatically stops the repetition. In case of reactive dreams there is no symbology af these are a direct copy of past traumatic experiences. Reactive dreams usually appear as the result of a traumatic experience from war, etc.
There are more categories and subcategories but I am going to simplify it on these four for now.
Why are dreams important
The health isn't just physical or psychological, both aspects are part of the sum and both aspects also influence the sum, so a psychological problem can influence our physical state just like a physiological problem can influence our mental state. Dreams as the direct output from the unfiltered unconsciousness give us a decent overview of both the mental and physical state and as such dreams are a very helpful aid for the introspection (practice of self-discovery). Introspection was heavily propagated by F. Bardon in his work but even nowadays many occultists do not care about its benefits.
How to interpret dreams
In case of dreams we have a double symbology, one is shared for all of us despite of our race or culture and one is individual for us and it's based on our personal lifes, experiences and character traits.
This could lead to the idea that by understanding just the symbology we can easily interpret our dreams, which would be false and gave us a very general meanings at best. Even the best dream interpreter in the world will give a wrong definition if he asks a wrong question.
The right question in dream analysis isn't what does the dream mean, but why did I have this dream and where should it lead me to. If you ask yourself these questions while analyzing your dreams, you will start to understand where I am going. The dreams try to either warn us, inform us or prepare us for something, that's why it's not important what does the symbology in the dream mean (well, it is sorta important but do not overestimate it), but why we had the dream to begin with.