When you’re deciding on a title for your book, try exploring your manuscript. There could be a good book title hidden there somewhere. There may be a cool passage that could be the title if a word or two were re-arrange in an interesting way. Also, in your book’s title, try placing keywords in there to make it more searchable online. And you could aways research online for the best selling titles in your genre. But a really good title comes from inspiration and is a bit unique.
Book subtitles are usually based on the genre. It says more specifically what the title cannot say. A subtitle can tell the reader what type of book it is. For instance, it may simply state, “a Novel”. You can use more words in the subtitle than in the title to convey what’s in your book. Also, it can explain how the book is structured inside. Using keywords in the subtitle helps your book be more searchable as well.