Choose a subject you love, then research it to make sure you have a substantial audience. If you promote what you love, then your passion will show, be contagious, which will ultimately lead to your success. Also, you'll have lots of fun.

NicheQs are good, but of course if you're inspired by another niche or don't know how to find one, you can go to the "research" section in the training center to learn how to pick a niche. :) Good luck and congrats on taking action early! :)