A preface includes scope, "reasons for undertaking the work, method of research (if this has some bearing on readers' understanding of the text)," and acknowledgements, which may be alternatively in separate section. An introduction about the subject matter of the book belongs "not in the front matter but at the beginning of the text, paged with Arabic numerals." (Quotations from Chicago Manual of Style, 15th ed., 2003, sections 1.49 and 1.53.)
You may tailor the items below to your book. Some of these items may not be appropriate.