First: do not quit your job (yet). A steady income will not only give you money to pay bills and buy rice & beans, but also the mental freedom to take time for yourself at night and weekends to start a new business.
Second: use nights, weekends & holiday time to study awkward and neglected business niches. It can be anything from stamps, to girls’ bracelets, dog’s collars, whatever. These niches are most of the times too small for deep-pocketed players to enter into, but big enough for small players to enter and profitably market their products without big marketing investments.
Third: once you have found an interesting niche, start selling your products there through one of the many available online portals (it can be Amazon, or Etsy, or Ebay). You will understand that every niche has its own preferred channel: use the most common one to achieve the initial lowest selling friction. Once you have learnt how to use this channel, you can start selling on different channels so to (hopefully) multiply your results.Action is very important. Do not think too much, do not wait to have the best product ever. As soon as you will start selling you will acquire knowledge of your market niche and you will learn from your mistakes (even if you are not able to sell at all).
Fourth: periodically evaluate your results. If you are not making at least 1000 USD of monthly profits after approximately the first 3 months, you must re-focus on a less exploited / more fertile niche. Margin is essential. This is just a business: you are not marrying your next wife. If it does not work, learn from your mistake and move on.
Fifth: after a few attempts you will get better (and luckier) and find a profitable niche. Once your own business stars yielding approximately 10k USD a month of monthly profit you can evaluate whether to ditch your job and focus exclusively on your own business.