Dreams are very common, and have been documented throughout the Bible as a medium in which God will choose to communicate with people. In some cases we can interpret our own dreams and understand their meaning clearly. Other times the meaning and message communicated in the dream can be above our skill level to understand, though we may be perplexed by it. This is exactly what happened in the book of Daniel. The king had dreams, felt they were some how important, and summoned his servants to offer interpretations as to the meaning.
Such an example is a perfect model for anyone offering a dream interpretation service. Basically one person has the dream, and they work together with someone else to help bring the message to the understanding of the dreamer. The dreamer and the interpreter work together, sometimes over the course of a few hours, to understand and decipher the symbols in the dream, and come to a conclusion as to what the dream means, or is saying.