Blogs are wonderful tools to engage with your readership, however they can get a bit cluttered when it comes time for book promotion and online marketing. If you are going to keep a blog but no website make sure your headers are easy to spot and access and give it a website feel.
If you can do a website and blog I would highly recommend keeping the aesthetic style similar to show continuity and connection. Also, make sure they link to one another so readers can bounce between the two. Or make one the micro site of other.
No matter what you choose, make sure your pages clearly link to your social media sites and you social media sites send people back to your webpage or blog.
If you don’t like to update often: choose a website. There’s nothing less effective than an empty blog that is a place holder for when news comes along. A website can be your business card, just put up the key information or have someone design something very simple. And if you do end up wanting to branch out, you can add a blog as a micro site. For fiction authors starting with a website is a good idea so your readers can find you, find out more about you, and find where to buy your book.
If you have lots of information to share and you have time to update often: choose a blog. If your subject matter (like non fiction, or something visual) would keep you busy with lots of great things to post, a blog is a great way to build you community online. A blog will also let you know if there is a market for your book and if people are enjoying connecting with your material. However, you can’t duplicate all the information from your blog into a book–publishers want new information so they feel they are brining something new to bookstores and your readers–so be careful you don’t show your whole concept, upload all your photos, or share your entire argument and research.