Once you get what a niche is, finding become a bit easy. The following tips would help you.

Your area of expertize

What is your area of expertise. May be that can become your niche in which you provide solutions or entertain audience.

Finally the success factors.

There are lots of factors that would play an important role in your success. The following are the few to look at.   

• Time  - The more time you put in your site, the better.
• Money - You need this to promote or market your site to increase traffic or need to provide for you daily operations cost etc. Keep in mind if you want to make money from you site, you have to balance out as what you spend.
• Team - Having a team to do the same job can easily outperform the work done by an individual. So start thinking if you can expand from one to two or more.
• Idea - The Idea is key here, you have to have a clean vision or perhaps refine your vision as you go along.
• Content  - You would have heard "Content is King" and that even true today. However now it means unique content to be precise available to be consumed at the earliest.