Designing for Results
Finally, it's time to think about your own goals, too.
What do you want to achieve with your blog?
I have deliberately put your readers' needs and goals first: if you don't meet those, you don't even need to think about meeting your own goals. Because you will have no readers.
There's nothing wrong about ads, newsletter subscriptions, and product sales - if you keep these goals in a healthy balance with your readers' goals.
Take the time to explicitly think about your own goals. It will help you structure and design your blog accordingly.