Perhaps you work as a threat analyst (Related: What is Cyber Threat Intelligence) for a company and you've been tasked with gathering intelligence (Related: How the intelligence cycle works) about your executives so that you can understand their exposure online. Or perhaps you're participating in online challenges like Capture The Flag events. Either way, you'll want to use three key search engines:
Each has its strengths and weaknesses. If you've never heard of Yandex, it's the Google of Russia. Yandex is superior when it comes to Europe (and Russia obviously). Yandex is also good at facial recognition and landmark detection. Google and Bing are strong in North American regions. Latin America, Africa and Asia are tricky and you'll want to use all three engines to find what you're looking for. Below are three GIFs showing where to click to upload your image.
There's a site called OSINT Combine that provides Google and Yandex results all on one page. This might be a good page for you to bookmark for future reference.
If you've got a picture of a scene or interior, you can use photo editing software like Photoshop to remove people from the scene to try and trick these engines into searching better. People can throw the engines off. Your editing skills don't have to be amazing, just a rough colour block to trick the engine. It can be as crude as this:
This is a short and sweet article on reverse image search, the main thing to do is: practice. The more you do it, the more familiar you'll be with all the tools at your disposal.
If you'd like to see a video of these tools in action: here you go!