As you probably already know, contacting niche magazines for book reviews, editorials, or articles related to your subject matter (wherein YOU are the expert) is a fantastic way to promote your self-published book.
What is advantageous about niche magazines is that they are more receptive to submissions and inquiries, particularly if it is within their niche.
What is disadvantageous about them is that you need to make sure your inquiry matches their niche in some way, and refer to that connection in your pitch.
There are SO many niche magazines out there that you should conduct your own search for them on the Internet, but here are two that you may work for your book:
DIVORCE Magazine is a bi-annual publication geared to people who have had, or are contemplating divorce. Segue Esprit is the publisher of both the print version and the Online publication at http://www.DivorceMagazine.com. Their editorial offices are at:
2255B Queen St., East, Ste. 1179
Toronto, Ontario, Canada M4E1G3
Gulf & Main Magazine is a bi-monthly lifestyle magazine. Patricia George is the editor-in-chief.
Gulf & Main Magazine
1422 Hendry St., Ste. 304
Fort Myers, FL 33901
Good luck and have fun!