Animals
A dream about a particular animal often means that certain qualities of that animal are significant to you right now.
Think of what that animal symbolizes to you, and what the standard ideas about the animal are. For example, a mule is usually thought of as stubborn).
Notice what the animal is doing in the dream, and how they are doing it. For example, a dog who is digging a hole may mean that treasure lies in hidden places and you'll need to go looking for it.
Colors
Often represent moods, feelings, or a sense about the object or situation where the color appears. Colors that stand out in a dream (not just the various colors of the dream setting) are often very important symbols. For instance, a person wearing all black can mean your subconscious is portraying them as sad or mourning a loss, or as very formal in their manner or style. Consider also the hue and brightness of the color. For example, a bright green could represent something different from a drab green, or a pastel green.
People
A person in a dream can represent that actual person, or the characteristics you attribute to that person. Meaning, if you dream about your boss who is always in a hurry, your boss may represent himself, or he may represent the idea of hurrying: feeling like you need to hurry something, or that your hurrying too much or need more patience, for example.
Also, the significant symbolism of a person in a dream may not be who they are, but what they're doing, how they're doing it, or their attitude - anything that stands out about them. Pay attention to how the person appears, as well as what the actual person symbolizes to you.
Emotions
Emotions in dreams often represent themselves, although the subconscious mind may be exaggerating them in the dream. For instance, if you are feeling angry or happy during a dream, you are likely truly angry or happy about what's happening in the dream—and also about what it represents in real life. Emotions of people other than yourself in your dream can represent a state of mind you're imagining, expecting, or fearing—especially when the person is someone you know in real life. The emotions of a stranger or strangers in a dream can also represent something you're imagining, expecting, or fearing. An angry stranger in a dream who comes up and hits you could represent your feeling that the world is an aggressive or negative place, or a recent real-life event where you experienced someone else's anger—or anger in some context that happens to be on your subconsious mind.
Objects
An object in a dream often represents the characteristics you attribute to that object—what that objects usually brings to mind when you think of it. Meaning, if you dream about your watch that has been stopping a lot lately, your watch may represent your feeling that you're life has felt "stopped" or held-up or interrupted lately.
Also, the significance of an object in a dream may not be what it is, but it's context—how it's placed or being used, where it appears. For instance, an object that's out of place or in an unusual place can mean that whatever that object represents in real life feels "out of place" or off right now. Pay attention to what stands out about the object, as well as what the object itself symbolizes to you.
Places
Places can indicate the setting of a dream, a mood, an event, or many other things. For example, many people dream that they are in a house—which usually represents the dreamers life or one aspect of their life (home life, work life). A dream that takes place in a graveyard can indicate a dreary, dismal, or depressing mood or a feeling of dream or sorrow. Dreaming of a Superbowl stadium can represent an actual game or something that is sporting or game-like.
Events
An event in a dream can represent an actual event in your life (usually a recent one or something you are worried might happen in the future). An event in a dream is almost never a prediction of a real life event - much more often it represent a fear or hope of something like that happening in real life, or the subconscious might be exploring what it would be like if something like that happened. So, events can symbolize fears, hopes, desires, curiousities, preparedness, among other meanings.
Parts of the Body
A part of the body (knee, elbow, head) often represents one of the main functions of that body part. For example, dreaming that you break your leg can represent trouble moving forward or making progress in your life, since the legs are what enable you to literally move forward when you walk. Dreaming that you can't open your mouth to talk might mean you're feeling stifled or somehow unable to express yourself right now. Occasionally, dreaming about a particular part of the body can result from actual physical pain or other sensation in that part of your body while you're sleeping. For example, dreaming that your head has swelled up 10 times its normal size could be a result of an actual headache while you're sleeping.
Activities
A particular activity or task in a dream can represent that actual activity in your life (usually something you've done recently or is on your mind for the future).
Also, very often, an activity represents something completely different, but with some similar characteristic. For instance, dreaming that someone steals your keys often means you're feeling like you're losing your self-identity, or that someone or something is "crossing your boundaries" - or you're afraid they will.
An activity in a dream is almost never a prediction of a real life event - so dreaming that you're a guest on Jay Leno doesn't mean you should brush up on your witty conversation. Much more often an activity represents your feelings during that activity in real life recently, or a fear or hope of something like that happening in real life, or the subconscious might be exploring what it would be like if something like that happened.
Attributes
A characteristic of a person, place, thing, activity, etc., especially if it stands out or seems unusual, often shows an amplified version of your feelings or impression. For example, in a dream about a dog, what color was it? Did it look healthy? What was the dog doing, and how was he doing it? Was the dog's tail wagging? A mean or angry dog would mean something completely different than a happy or friendly dog. Pay attention to attributes, characteristics, and contexts for more detailed clues about a dream symbol's meaning.