Just thought I'd let everyone know about this site which I've just discovered
. Mercedes has written a large number (sometimes multiple articles posted per week) of very well written articles on all aspects of DNA research, covering all the main sites - 23andme, Ancestry, MyHeritage, GEDMATCH, and tools like DNA Painter.
http://whoareyoumadeof.com/She also has an e-book which you can download for $10
https://mailchi.mp/e5b4f224571d/understandyourdnaresults