One of the topics most interest to people that we are working on the Internet, they are the market niches, let's start by saying that if we are clear that what we're passionate about, it is to achieve income through the Internet, no matter what niche market we dedicate as the first step is to learn.
One of the errors often committed is start selling products to lose weight, and the following month products to quit smoking, then the law of attraction and finally products of gardening. This shows that there is no a single niche market and therefore does not have the success that you want to.
The best tactic is to choose a topic and learn the most about this topic, i.e. learn to generate qualified traffic made products of our theme, build a list, and of course a database.