In addition to our own improv blog we also recommend the following:
Chris Mead, Hoopla teacher: https://www.chrismead.co/blog
Katy Schutte, Hoopla teacher: http://www.katyschutte.co.uk/improvblog
Will Hynes, Improv Nonsense Blog: http://improvnonsense.tumblr.com/
Jimmy Carane: http://jimmycarrane.com/blog/
Mick Napier, Annoyance Theatre: http://micknapier.com/blog/
Patti Styles: http://pattistiles.com/category/impro-blog/
The Phoenix Remix: https://thephoenixremix.com/
Stephen Davidson: https://impromiscuous.com/blog/
People and Chairs: https://peopleandchairs.com/
Dan Goldstein: http://www.dangoldstein.com/howtoimprovise.html
We also have our own improv blog.