Deciding on which niche you are going to blog about can be one of the most grueling task imaginable because since their are almost one thousand blogs going up each day, almost every topic has been chosen . Don't worry because just like traditional businesses too have a lot of competition too. So, even if you are an so called expert in a certain field their is always someone to trump your expertise. SO the next big thing I would say is to develop a sub niche .Like take for example your niche was luxury cars , a sub niche of luxury cars would be a Bentley.Since their are so many people in the same niche I think personally it is better to come up with a sub niche and completely focus on it. This tactic will bring loads of traffic from Google because you have more content on a single word than having so many keywords with little content.