A lot of people live from the monetization of their blogs. As EndaMac said above, you can go the quantitative way - dozens of blogs with good keywords, relevant content and add a combination of affiliate links and Adsense. (Careful - If the quality is poor, it will inevitably fail!)
Or you can go the other way round - the qualitative way with ONE quality blog that solves a specific problem for your niche and you will be known as THE expert in within that specific niche. It will take a little bit longer but the rewards will be greater. (You will actually build a business!)
You will need to choose the right niche and know it inside-out.
- Who are they? Where do they live? How?
- What are their problems, their main obstacles?
- Where do they hang out online?
- What solutions can you bring?
- How can you solve their problem? Can you do it yourself, with other people products/courses, etc?
By researching and writing on this, you will become very knowledgeable on the subject and will want share your findings, tips, secrets to them on a regular basis.
Keyword research is also important but not as much as with the first method because your traffic will come from within your niche and to a less extend from search engines.
Traffic will also rely on the many meaningful online connections you'll make and the set up and growth of your own mailing list.
This is often referred to building your "YOU,inc." - Personal branding is key to your success in this kind of activity. (I can recommend a couple of guides and experts on this...)
The secret to this method is to give out 80% of your stuff for free and you'll make a good living from the other 20% - Once you have build trust and shown your knowledge, people will follow you (...and buy from you or follow your recommendations).
The monetization of my blog comes in different forms:
- from affiliate links (courses, service providers, marketing products)
- and from my own products (consultancy, offering my services and in the near future selling my own "how to" guide)
I have chosen that route and I love engaging with my audience in the numerous way that the Internet offers us while earning money and having the freedom to travel around my new country of residence!!!