Upper Intermediate Learners : What is the best way to improve your English speaking skills on your own?

Hi there

 

I was asked this question by one of my students, and as well as giving them my answer I'd like to hear what other people think. 

 

Aside from formal lessons in the 'real world' or online via italki, what else works really well for you?

 

Look forward to hearing your thoughts

 

Chris