according to using blog is best for more such as SEO, particular topic in brief so using blog is best.
Another good method is to study what the successful bloggers are doing.. what kind of posts they write, etc.. like johnchow.com and zacjohnson.com. Go to their blogs and spend time reading and studying their ways and methods. I remember reading a free guide from Zac and he mentioned that there are a few kinds of posts which people normally like to read, eg: personal posts (not outsourced articles) relating your personal life, posts relating to case studies, results, tests, etc... You should study these and apply it to your niche... All the best!
to earn money you should have to make multiple blogs on different niches also you need to spend maximum time and efforts on your blogs promotion then you definatly can earn good money from these blogs.
According to my experience blog is most important to know any topic. From blog you can know more about any topic.