Web coder Swagat Kumar Swain has put together a handy list of commands you can use with Chrome’s developer console, though there’s nothing stopping you from using them with your browser of choice (verbatim or with a few tweaks).
Perhaps the most useful is live page editing using
document.body.contentEditable=true. Other useful tips include event monitoring and even timing the execution of your code:
One piece advice I’ll likely use in the future is selecting DOM elements via the console. This can certainly be the easier option than inspecting via right-click for hidden or otherwise obscured components.