1. not spending much money upfront
2. not needing much experience, specialty
3. is relatively in high demand
http://www.frugalhack.me/2016/09/28/how-to-sell-on-amazon/ is long but will bring you up to speed quickly.
Everything else is execution.
Also you could easily drive for uber or lyft.
ok so a business, i run many. i build websites, design mobile apps, write books or blog posts for news sites, sell stuff on ebay, do video / photo work for the community.
what r u looking to do?