The two main functions of dialog are that dialog must define a character by make them unique (unique dialects, manners of speech, types of phrases, not “out of character,” etc.), and it should help move the plot forward.

Dialog is often where an individual can voice their feelings and emotions.  Keep in mind that certain genres might have unique dialog, such as westerns.  The nature of the book will also shape the dialog.  For example, readers don’t expect long dialogs in adventure or thriller books. Dialog in books is more direct and clear than real life conversations.

Also don’t be embarrassed about what comes out of a character’s mouth; the character is not an extension of your own personality. If this were true, all of your characters would sound the same, and the book would have no variation.  After a while it would become bland reading.

Mix up your dialog with different dialects and personalities.  Use the most of well-developed dialog, and don’t bury it in long conversation. A good verbal exchange at the beginning of a chapter has a way of pulling in the reader.  Another useful tip is to rewrite dialog from other authors.