[crazygringo]

Have there been any improvements in noise reduction?

That's what's always kept me from using Audacity in the past. I like the interface and operations and everything, but cleaning up audio (removing room tone mostly) has always been the first step in my workflow, and its built-in noise reduction has just been unusably terrible compared to basic commercial tools.

Or is there a common plugin people use with it that I've never known about?

[lotsofpizza]

Typically a noise reduction plugin installed with the DAW by default isn’t going to be amazing. People usually install their own preferred plugins when using a DAW. If you look up noise reduction VSTs you will get lots of results for paid and free plugins compatible with Audactiy. I don’t have a recommendation but googling “reddit cheap noise reduction vst” came up with a lot of viable recommendations.

[eliasmacpherson]

if you were on Windows you could possibly do something to get this into Audacity:

http://reaper.fm/reaplugs/

https://github.com/nbickford/REAPERDenoiser