Derek Murphy is a book designer with a Ph.D. in Literature. He’s been featured on CNN and spoken at dozens of writing conferences around the world. These days he mostly writes young adult fantasy and science fiction, while helping authors build profitable publishing platforms.
Free book cover templates and design tutorials: https://creativindie.clickfunnels.com/clickpop-9889264
Other website and freebie mentioned: http://diybookformats.com/
Guerilla Publishing ($2.99 on Kindle): https://www.amazon.com/Guerrilla-Publishing-Revolutionary-Marketing-Strategies-ebook/dp/B01MQP5740
CreativIndie.com (check the right hand side of his website for a free download of 4 books)