I began reading Heinlein with Stranger in a Strange Land (great book). After reading that and expressing my liking of his style, a friend of mine introduced me to his Future History series. It was advertised to me that this was the first, but Wikipedia seems to say otherwise (http://en.wikipedia.org/wiki/Future_History). Either way, this was a great, short book to read. Heinlein had some really interesting ideas, and it is my understanding that this may have been the first book that introduced Lazarus Long - a recurring character in his books.
