Vast majority of my followers are writers (I needn't say that all writers are voracious readers) and publishers. Your book is surely going to get attention.
I will use the two most popular hashtags - #books, #kindle. You can also suggest me a hashtag (e.g. your genre specific one - #romance, or #thriller)
Don't hesitate to give me a shout if you have any doubts or need a customer offer.