If you want to market your book using twitter, start by creating an adequate profile, with preferably using your own name so that people can find you. Also write an intriguing bio so that people who spot you want to follow you.
Interact with other writers of the genre you are about to write in or already have written in. People have to know you exist, so tweet, RT, and message. Also twitter etiquette requires that you follow those who follow you and no trolling please!
Follow the greats and learn from them. Neil Gaiman and J.K.Rowling know how to keep the twitter buzz alive, and have followers in the millions.
Tweet often as internet memory is zilch. You can use tools like Bufferapp or Hootsuite to schedule your posts in advance. If you’ve written a book, don’t hesitate to tweet about it. Tweet your blog posts and whatever it is that you are writing. Also you can offer discounts for your book on twitter. Post pictures of what reflects your book or your personality. But remember that all your posts should not be about your book. That becomes boring.
Retweeting is good and Favoriting is better! Use the hashtag approach if you want to get noticed. But your tweet shouldn’t be all hashtags either.
More links about online marketing in 140 characters here:
http://www.cio.com/article/2380667/twitter/14-ways-to-use-twitter-to-market-your-business.html
http://www.makealivingwriting.com/writers-win-social-media/
https://www.theguardian.com/books/booksblog/2014/may/27/10-authors-who-are-brilliant-at-twitter
