This tip comes from the Knowledge sharing challenge.
You may already know that dashboards are represented in configuration as simple json files. These are what you work with when configuring them through the API. An update recently made it possible to work with this json directly in the UI.
This makes it much faster to copy dashboards between environments or to copy or modify some sections in bulk. You can simply copy a dashboard from your QA to Prod environment and change filters etc... instead of trying to replicate the dashboard tile by tile. There's also the standard tricks you can do with text in a text editor such as find and replacing text for example if you wanted to find all occurrences of 'qa' and replace it with 'prod.'
Stuff like this had already been available through the API but with it in the UI you can make big changes in seconds especially if you keep configurations and conventions consistent across any environments you have.