Ask for a raise. If you’re unhappy with your compensation at your 9-5 job, asking for a raise is one way to beef up your bank account. Most employers offer an annual review of your work – which could be the perfect time to negotiate a higher salary or ask for better perks. If your employer doesn’t offer such an opportunity, it might be time to initiate a review yourself.
The topic you choose must have enough depth that you can create a lot of content for it. This is important for building an authoritative site, for search engine optimization, and most importantly, for the end user. If you don't have enough content about a topic, you're not going to be taken very seriously as an authority on the topic and it's unlikely you can convince someone to make a purchase from you.
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.
If you’re willing to take on some risk and have the heart of a true hustler, you can make extra money online doing commission-only sales for startups and other businesses. While you won’t be getting a regular salary, with the right sales strategies and skills as an inside sales rep, you can make decent money for each sale you bring in. And because you’ll most likely be working with startups, if you can negotiate a little equity you could profit big time if you're pitching a solid product and the startup succeeds.