Always, always, always capitalize your book title. There are words you shouldn't capitalize, but there's a lot of variation in the rules about this. A good general rule is to lowercase minor words that are three or less letters long ("a," "an," "the," "and," "or," etc.), unless they start or end the title. Nouns are never minor words, so always capitalize those, regardless of length. The rules can get pretty complicated, so if you're ever in doubt about a particular word, you're not wrong to capitalize it, and if you can't figure out which words not to capitalize, it's fine to just capitalize the entire title.

Examples:
Capitalization with lowercase rules (my preference): SPAG, the Culprit of Lost Marks and Other Assorted Writer Woes
Capitalization without lowercase rules (not my preference, but okay): SPAG, The Culprit Of Lost Marks And Other Assorted Writer Woes
Only capitalizing first letter (not okay): SPAG, the culprit of lost marks and other assorted writer woes
No capitalization (not okay): spag, the culprit of lost marks and other assorted writer woes

As far as chapter titles go, this is your preference. I like to capitalize my chapter titles, but there are authors who don't, and that's fine. Just keep it consistent. If you use one set of rules for one chapter, do that for all of them. I really don't like completely uncapitalized chapter titles, but it's your stylistic choice, and if that's what you want to do, again, just be consistent.

Now, how do you refer to a title in the text of your story? That's up to you, but again, just be consistent. I like to italicize book titles, and I carry that over for document titles, album names, song titles, etc., so when readers see italics in the text, they know what that means. You could also use quotation marks (single '' or double ""), underline, or bold, whatever works for you. I'll discuss the use of all these methods to set text apart later, but long story short, try to keep these special. Don't use them too often. If you do, they don't stand out anymore.

And, after all that, I found a website that does the work for you. Click the "External Link" button below the "Continue to next part" button to go there, or click the link in the inline comments here. →