I had a book designer look at one of my covers who thought it was fine except for the font. The takeaway for those of us trying to get by with what's free and what we have, is to keep it simple.
I spent several hours looking for an Arts & Crafts style font and didn't turn up with anything I thought would work on a cover. The one I thought would work carried a price tag.
The Art & Crafts movement started in England with people like William Morris and Charles Rennie Mackintosh in the 1800's, not stuff from China you buy at the hobby shop. When it came to America, designers like Gustav Stickley, Elbert Hubbard and a whole host of others created a Craftsman style inspired by the California missions. Hence Mission Oak furniture. Square, simple and desperately uncomfortable.
That's what I wanted for my mystery set on the Central Coast of California with a mission in the center of the valley. Couldn't find anything useful so went to a Celtic font which is close enough.
The question is--do you attempt to find a font that is somehow linked to the book or do you just go for an unadorned font that will convey only the title and stylistically recede into the background. I don't know the answer this morning.