You should never put all of your hope into one online job. It's better to have more than one online source of income. The reason for this is because the Internet is always changing. While one day a business could be thriving, you never know what could happen to that source of income.
Medical transcription can be a good way to make money online as a full time career. Formal training is required, and this can be costly. Additionally, it is necessary to have good computer and transcription equipment that works reliably. A great deal of work is available for people who are able and willing to invest in training and good equipment. Pay is quite substantial.
Create an interesting blog. Make posts on it regularly. Work through social media sites to drive visitors to your page. When the site is popular, you can sell ads on your website. If a visitor to your blog clicks on an ad, you get a cut.