A great article about letterspacing type while designing for the web. In short, follow a few simple rules...
- Capital letters - it's always good idea to increase letterspacing when using capital letters.
- Font size - as size increases, letterspacing decreases, and as size decreases, letterspacing increases.
- Font weight - as weight increases, letterspacing decreases, and as weight decreases, letterspacing increases.
- Light-on-dark text - light type on a dark background usually looks better with an increased letter spacing
Effectively letterspacing text can make the difference between good typography and great typography.
https://johndjameson.com/blog/guidelines-for-letterspacing-type/