With beginnings, we often worry about making the very first sentence the very best. The sort of beginnings that resonate through a reader, that stay with them forever. Such emphasis is placed on achieving such a thing, that many writers trip up and never begin at all. Instead, strive to make your beginning a beginning, not a masterpiece in itself. Begin your conflicts, your characters and your atmosphere. Impressive sentences tend to be found when you're not looking for them, so deal with that when editing. For now, think about what comes after that sentence.