how do people even search for specific topical related blogs. In my case it's a blog for sales professionals.
What you might want to think about instead is "what kind of content is a reader going to be looking for." I would assume most people don't set out to find a blog.
Think about how many people found stevepavlina.com because they were looking specifically for a good personal development site. I think it's much more likely that they were searching for a specific topic, maybe polyphasic sleep, maybe productivity.
Apply the same thinking to your own blog. What will your potential readers have problems with. What will they need advice on or be interested in? This is a good way both to come up with good keywords and to come up with post ideas as well.