The word flashback often causes many writing instructors and editors to say, "Eesh. Not this again." When handled carefully, flashbacks are effective storytelling techniques; however, using them with reckless abandon can significantly confuse readers.
My philosophy? Never throw out a potentially useful tool in your story. There's always a fine line to consider when utilizing flashbacks, just as with other storytelling techniques. Authors should always be careful not to use too many flashbacks, especially in the beginning of a novel. As a writer, you never want readers to ask, "Why didn't the author start here, in this setting or in this time?" Messing with chronology and pacing is no joke. You want readers to focus on the plot and characterization, not the order in which things occur or how certain information unravels.