Alexia, you can right click on the paragraph you want not indented, select 'paragraph', and under "indentation", click the drop-down box where it says 'first line' and select '(none)'.

Or get embroiled in Styles, and set up one Style for indented paragraph, and one for first paragraph. But that's tiresome if you've only got two different things you want to do.

Thanks, Emma - both methods seem a bit fiddly! I'm thinking I might just give up on preset formatting and use the tab key instead. It's good to know I'm not missing something easy and obvious, though!