Rangers Apprentice: The Early Years by John Flanagan.

Rangers Apprentice: The Early Years by John Flanagan is a great prequel to the rangers apprentice series. This book is set after "The Hibernian" one of the short stories in "The Lost Stories," and even without reading "The Hibernian" you can still enjoy the story. That is one thing that john flanagan does really well in all his books. The book explains some of the history behind parts of the main series, (one I would highly recommend reading) and is a good read as a standalone. This book is set from the perspective of Halt, a grizzled ranger who eventually becomes Will's apprentice in the main series.

Etiquette and Espionage by Gail Carriger

Etiquette and Espionage by Gail Carriger is the first book in a great series about Sophronia, a tomboyish young lady who, due to her antics, is enrolled at Mademoiselle Geraldine's finishing academy for young ladies, which, at first seemed like a very dull school, but once enrolled, she finds the classes interesting, not only including the necessities of a finishing school, but also adding classes such as classes on espionage and poison. "Algebra was far more interesting when it was a matter of proportioning out mutton chops so as to poison only half of one's dinner guests" During the first book, Sophronia makes two friends, Soap and Dimity who accompany her on her... Endeavors.