I recently discovered a site called Canva from Lucyface, and let me tell you, it is lit for minimalistic cover designs! With that, I'm using a double exposure app called Blend Editor - it's free and the best free one (cause I only use free, lol XD) I've used to date (December 7, 2016)!

Also, all three middle ones, I've redesigned!!! You can check out the design they had before this Canva layout! XD

The last ones, I created for TheWriterD and SallyMason1 (respectively).