I recently went on a Collage & Mixed Media course. It was really enjoyable and I learnt a lot.
The first exercise the tutor got us to do was designed to make us think about drawing in a different way. Borrowing a phrase from Paul Klee, she taught us how we could 'take a line for a walk'. First she gave us an object to hold and, once we had closed our eyes, we had to draw what we felt whilst not removing the pencil from the paper. Then, with a second object, we had to draw what we saw but we weren't allowed to look at what we were drawing.
We then did some mark making. First dry on dry ...
and then, wet on wet.
We then went back to our line drawings, and cut out shapes from our mark making to add them to our drawings.
Here is another, where we added paint to our collages.
I'm not sure that I would want to hang my collages on the wall, but it was a very interesting exercise and one I am sure I will use again.