@grimalkina
Tip #3:
Don't neglect what's going on.
We where so busy with the production and with taking his mind of the chemo, we did not realize the moments he just wanted to cry. This is the biggest mistake we made back then. Don't do it.
It's difficult to differentiate self pity from honest sadness and overwhelming.
Learn the person in front of you and find the sweet spot between pushing positivity and a big bear hug.

And after all, nothing I worte is wisdom or common sense, this is what I experienced with one person. You're friend will be different and the opposite might apply.

Again, you're already doing the most important thing: You're there!

I wish the very best for you and good health to the person you accompany.

@grimalkina
It's a tough thing you are about to do. And the most important thing you're already doing. You'll be there.
Once I worked with a colleague who went through chemo while we were in production of a play. He was the responsible for make-up and special effects. We never talked about his therapy, he didn't want to, he wanted to be in that moment.
First tip: focus on the things the person CAN do, rather on those not possible at the moment.
Second tip: don't pressure.
One day the guy was unable to be with us for a show. We all knew and nobody mentioned it, nobody pushed him with nonsense sentences like: You can do it, I know you can!
We tried our best and in the midst of chaos we called him asking a couple of questions. Je was exhausted but helped and I believe he felt being a part.