There are countless methods of dreamwork, each with its own merits. Here are some basics to get started from a Jungian perspective.
Jungian Dream Analysis
Carl Jung looked at dreams as a collection of symbols that have unique meanings for each dreamer. Rather than assuming that there is a preset group of symbols with universal interpretations, Jung acknowledged that the images that show up in dreams will be deeply personal to the dreamer - with a few caveats. One being that water tends to pretty universally represent emotions, and two being that houses/buildings tend to represent the dreamer's psyche. These two aspects of a dream - water and buildings, will of course, still be unique to whatever is going on for the dreamer.
Working With a Dream
Writing down your dreams first thing in the morning is a great way to train your brain to remember them. Dreams tend to fade away even within the first few minutes of waking, but getting in the habit of writing them down quickly can help you remember them more easily. Choose a dream or a piece of a dream that you remember well. It will be easiest if it's a dream that feels almost like normal life plus a few strange quicks, rather than a chaotic dream with lots of layers that fade in and out of other story lines. Once you have your dream (or dream fragment) replay it in your mind, or share it out loud with a trusted friend. Traditionally dreams are retold in the first person, present tense to deepen the experience of being in the dream.
As you go through your dream, take note of the landscape, weather, time of day/night, atmosphere, scenery, objects, people, emotions, plants, animals, buildings, doors, windows, smells, sounds, textures, etc. It can help to make a list of the content of the dream, including anything notable that is left out (i.e. "I knew that it was night, but I couldn't see anything that indicated this.)" Now go through your dream in the same way one more time because new details often come up the second time around. Finally, go through each thing on your list and explore your associations. Associations are basically your thoughts and feelings about a thing, informed by your past experiences, preferences, emotions, aspirations, etc. For example, if there was a small clay bowl in your dream, think about your relationship to small clay bowls, pottery, art, the color of the bowl, the feeling you had when you saw it or held it in the dream, etc. Do you know anyone who does pottery? Have you always wanted to make a bowl like this? Do you hate it because it's an ugly shape? Does it remind you of someone or something? Is it exactly like a bowl that your grandmother used for storing random tchotchkes, and so on.
Going Deeper
As you explore your associations with all of the elements of your dream, pay attention to contradictions and things that are off or wouldn't make sense in waking life. Maybe there is a locked door that you're trying to open for most of the dream and you're really frustrated about it, and then suddenly it opens on its own. You might then look at things that have been feeling frustrating, impossible, hidden, or unreachable in your life. Is there something about this thing that might actually make it attainable? How do you feel in the dream when the door opens? Relief? Surprise? Or is it unsurprising as if it had never actually been hard to reach whatever had been "locked" away? As you work through the dream in this way, themes should emerge along with more clarity. It can help to pay particular attention to emotions (or lack there of) in the dream as well as current events in your waking life. If you get stuck, take note of the prominent themes, and set it aside for now. Things may make more sense in time.
Dreamwork is not meant to predict the future or tell you what to do with your life, but it can be a valuable tool to help with processing emotions and experiences. Sleep and dreams help the body/mind process the day on a physiological and emotional level. Exploring dreams can do a lot to deepen insight and provide clarity during challenging times.