The best way to build a dedicated audience for any blog is to carefully and clearly define its target audience right from the start, and then create content that caters to that audience.
Focusing on a niche audience and developing appropriate content specifically for those people helps to ensure there will be strong interest in your blog's content, plus it makes promoting the blog easier.
The more narrowly you define your target audience, the easier it will be to identify those people, cater to their needs with your content, and reach them with your advertising and marketing messages.
The target market or audience you identify for your online content can be defined using one or multiple criteria, or various demographic characteristics, such as:
•    Age
•    Club memberships
•    Education
•    Geographic area
•    Hobbies
•    Income level
•    Marital status
•    Occupation
•    Religion
•    Sex
•    Sexual orientation
•    Special interests
Reaching a target demographic on the web is relatively easy (much simpler than doing it using traditional advertising practices in the real world). Carefully designing your online marketing efforts to appeal to your target audience will help set you apart from your competition and pique the interest of Internet users who are inherently interested in what online content you're offering.