We would encourage you to select only one niche when starting your online business.
Remember, Paul recommends the following four niches when setting up your online business:
Weight Loss
Online Marketing
Personal Development
Stock Market/Investing
Your Own Business
Although it can seem tempting to create a business around more than one niche, this can easily lead to confusion and overwhelm as you will be attempting too much.
Having said that, Paul states that once you have replaced your income with your first online business/niche, at that point if you choose to do so, you may change niches.
Until you have successfully launched your profitable online business, we would highly recommend you stick with just that niche.