Are the blogs that you follow helping you to solve a problem you have? Increasingly I've noticed that the writers I follow the closest are those that are actively assisting me attain the goals in my life. These could be as minor as learning how to draw, or as major as becoming a better husband.
If you show your readers a direct path that will help them to solve a problem they're having, they will support your site and your efforts to bring them more solutions.
What are Your Strengths?
The process of becoming an authority site for many keywords is a relatively simple — if time-consuming — matter of assisting readers answer their questions with answers you already know. What skills do you already have that you can teach to others?
The point of starting with a list of your strengths is not to determine the answers to the questions your readers are asking, the point is to determine what the questions are. In the process of learning that skill you will have already tackled hurdles that your readers haven't even considered yet.
Explanation not Exploitation
So how do we turn this process of explanation into a profitable venture? The key is to find a connection between a product or service that you can offer as a legitimate solution to their problem. This can either be a solution that you design yourself or can be a specific software application that you can explain how to use.
For example, if you know how to animate short cartoons, you can create a site that details how to use the software that creates those cartoons. If you place an affiliate link to the software at the top of your site, your visitors will happily make that purchase because you've given them the solution to their problem of "how to make cartoons". The solution isn't the software, the solution is your explanation of the process of creating the cartoons that happens to involve the software.
Continuing the Concept
If your strengths can not be related to an affiliated product, you could create an eBook explaining your solution and offer that for sale. This concept could be extended to include a full membership site.
By solving the problems your readers are having you will quickly become known as an authority for your topic.