What's the best way to capture images from a document?

If you have the original Word version (and occasionally with pdfs), if you right click on the image within the document you'll get the option to "Save as Picture". This isn't always available - possibly depending on the version of Word that it was originally written with.

Alternatively, Windows comes with a screen capture tool as part of its Accessories bundle (either called "Snipping Tool" or "Snip and Sketch" - the latter will eventually replace the former). You can use this to capture the portion of the screen that you want, so make the image the size you want it on your screen and then use the tool to draw around it and then save.

If you're capturing a flowchart with text make sure there's no spellcheck or grammar check marks visible as these will be captured too.