After adding compression to your recording, you will likely find that your "S" sounds are too sharp. On certain speakers, this can result in annoying distortion. As a result, it is often essential to use a "De Esser" VST plugin after using your compressor plugin.
A De Esser plugin is able to isolate all of the S sounds in your track and turn them down. The De Esser that I use and rate highly is called Spitfish. Spitfish is part of the free "fish fillet" VST package that can be downloaded HERE. Once you've downloaded Spitfish, you will have to add it into Audacity, which you can learn how to do HERE.
Once you've added Spitfish into Audacity, you will need to learn how to use it. Here's a good tutorial explaining how to use Spitfish. Hope it helps!