Need Guide on Choosing Niche

Hi Guys...
I am new to Internet Marketing...

Now I am going to ask some questions you guys.

Which Niche is more Profitable Niche in SEO ?
How to select a correct niche to start blog ?
Should I chose Micro niche ?

According to some researches, these are some of the most profitable niches: fitness, health & beauty, dating, self-improvement, pets, how to make money online. You can choose a micro-niche for each one - but ideally you should have sufficient audience for it, and at the same time not as many competitors.