It all depends on your skills. I would recommend starting a channel on YouTube, because you can earn money as soon as you reach 1,000 subscribers. Here are my top tips for making a successful YouTube channel.
1. Create videos on topics many people search about, or topics that are trending, that way you will get way more views.
2. Be honest with your viewers and don't click bait. Click bait may get more views in the short term, but in the long term, less people will trust you and your channel will run out of new viewers.
3. Make videos that solve problems, as if you help someone with their problem, they will be thankful and may subscribe.
4. Always say what the video is about in the first 10 seconds so the viewer does not lose interest.
5. Never give up on creating new and exciting content to keep your subscribers interested. Never let money be your goal; try to help your audience.
This way, you will reach 1,000 subscribers before you even know it. Then you can start earning AdSense revenue, good luck!