How do I secure copyright of a novel and/or characters of my own creation?

Google copyright. You can also use the poor writer's copyright by mailing a certified copy of your book to yourself mentioning the name of the book in the contents of the package.

Copyrighting characters is not too bad, but forget copyrighting conceptual elements. No one will let you do that. (Look at it this way: If George Lucas could have copyrighted the big reveal as being the bad guy was actually the good guy's father, he would have. But he retained character rights and made a very large fortune on Star Wars characters.)

Since this question was posted on Y!A UK, I assume you live in the UK, in which case, your book and characters are already copyrighted, and you don't need to do anything more. Some countries, particularly the USA, operate a registry of copyrights. Registration is optional - if you don't do it, your work is still copyrighted in the US. The main advantage of registration is that you can sue for copyright infringement in a US court.

"Poor man's copyright" (post a copy of the book to yourself and don't open it, so the postmark proves you had the book on that date) is legally worthless.

I don't know what you mean by "distinctive conceptual elements", but the chances are copyright doesn't protect them. If it's something like a plot twist ("bad guy is really good guy's father" or "bad guy split his soul into seven pieces and stashed them in objects so he can't be killed"), copyright doesn't protect those.

Copyrighting your characters comes from getting your work released, but it is extremely difficult so that you can sue anyone for taking your characters until it's down to a tee. For illustration, in case you wrote a story about a younger boy named Harry Potter who had a lightning bolt scar and who used to be the Chosen One, then that would be copyright infringement. However, in case you wrote a narrative about an eccentric young girl named Lucy Lovegood who is a drug supplier and tries to become president, then that would be your own character (in evaluation to Luna Lovegood from HP). It is all a topic of you now not being able to legally use any person else's strategies verbatim. When you like the suggestion of a lightning bolt scar, that is quality, use it. But when you use a mixture of too many things and your characters come to be too virtually different characters, that is when you're slicing it to shut. As for a better answer to your query, sure, characters may also be copyrighted, but the possibilities of you winning a lawsuit for any individual 'stealing' your characters are slim to none.

Once published, your story will be copyright automatically to you the author. But you cannot copyright ideas and concepts. Here is a really useful factsheet on copyright law in the UK (other countries will differ).

http://www.copyrightservice.co.uk/copyright/p01_uk...