You can work as a virtual assistant through dedicated websites, such as Upwork or Zirtual. All kinds of skills are needed, and compensation can vary anywhere between $10 per hour to $100 or more. Obviously, the higher pay will be to people who have more technical skills, such as web building skills and marketing. But you can find work doing administrative tasks at the lower end of the pay scale.
If you have a good idea for an app, and the skills to create it, then producing your own premium app can be profitable. However, with so many free apps available, it may be hard to convince people to pay. If you want to go down the premium app route, consider having a basic free version to encourage people to download the app in the first place. You can then provide the option of upgrading to a premium plan once users realize how useful the app is.