My boss asked me: "How can I help?" when I had a small breakdown at work (intense anxiety waves) He was very supportive, didn't cause any grief when I would leave in the middle of the day for therapy appointments, etc. If you're a friend, this could translate to picking them up for their appointments (for me, knowing there is a set time/date something is happening forces the getting out of bed, shower, etc) or scheduling a time to take a nice evening walk/go the gym. During this time don't bring up the depression unless they do. Talk about other things like hobbies and what's going on in the world.

My doctor asked "What do you want to do?" after listening to me explain everything for 5-10m. It was a great question for her to ask because I had ignored previous doctor on taking meds since I felt they weren't listening to me (as I was trying to explain how I was feeling he didn't even look up from his notes, cut me off mid-explanation and handed me a prescription to get me out the door.) This question from the good doctor (or simply one that had more time per patient) subtlety made it clear that despite what I was feeling I had some decisions to make and although I had support, the ball was in my court to put in effort on getting recovery going.

Also ask your friend if they have insurance through work. My company had a thing through Aetna where I got 5 free visits. Saved me $400-$500.