First off, you should have an expertise. I think by definition, most successful bloggers are in fact “Authority Bloggers.” This means that they have some kind of expertise that can help people achieve an end result in a particular subject.
That brand will hopefully have some “branded products” to sell at some point. For example, you can offer consulting , courses, books, speaking engagements, product representations, etc.
If it’s just strictly for money, using the blog as a product marketing machine, it might not be worth all the time. Largely because blogs have to be very niche specific, so you put a lot of time into a narrow field.