Humans love color. Bland websites will have people yawning and moving on. You need to have color. That means your website itself needs it along with having the cover of the books you are reviewing presented on the site. That will give it eye appeal.
Use events to grow your book review site. If it is the Fourth of July, have your website in red, white, and blue. Have games and giveaways. Make people want to come to your site.
Use visual aids where you can. Pictures are the first thing most people think of us and rightly so. Always use pictures. Think of visual aids you can add to your book reviews to help you draw in more readers.
Videos are really great to use. Everyone loves them especially when they are interesting and entertaining. Find some online or create your own. Just make sure they are appropriate for the page. Also, look for book trailers. Those can be nice as well.
Graphs can be useful too. This is especially true if you are sharing statistics. They are visual representations of numbers and help to show relations.