I attended a drop-by drawing session at the NGV last Sunday. It was facilitated by John Wolsely. I was surprised to discover that so many people are keen on drawing. It was catered to people with all levels; some families came and even the kids got involved.
John stressed that we should focused on abstract shapes, and the dynamics between them. We were asked to do some drawing. The session was short (only 2 hours), but I found it useful.
If you are interested, the sessions are free, and there is only one more session in January. This last session is on Sunday 27/1, and is facilitated by artist, Callum Morton.