We'll take it from a Nigerian who's been where you are now. There are numerous ways to make money in Nigeria, but it all depends on what your skill set is

Fiverr/Upwork: If you're a programmer then you can take up freelance jobs on fiverr, it may not be easy to get your first client, but it's all uphill from there. You can also work as a writer/editor on fiverr and see how that goes.

Steemit: Well steemit is obviously one of your better choices, as long as you're an active user then making a little or alot of cash will most definitely be a possibility.

Online marketing: You could become a Jumia sales agent and simply help people place orders on the Jumia website and receive a commission for all the sales you make. This is probably the easiest way to make money right now.

Tutorials: Well this is an offline method of making money and it simply involves teaching your juniors in school and charging them for the tutorials. It's a quick and sure fire way to make easy and fast cash.

Betting: Well I put this here because you may be the type of person that's good at predicting games well. If you are then you might find a home here. Please note that this is the only option you have where you could end up losing money instead. Please be careful.