These photos show a sequence of progress on one of my 24"x24" panels. They begin with loads of collage, carefully applied so that everything lies flat. Then they get painted, sanded, painted, collaged again, etc. in no particular order. In the video I'm doing a little hand-sanding.
This is a few layers of collage.
then paint
After a good sanding with the power sander
More paint...
more of everything...
some linework
lots of veiling and more line work...
And then some "reverse collage": I collage painted papers with the paint side down. When it's dry, I sand away some of the paper, and the paint shows through. Such surprises! This definitely takes you out of your "planning" mode. You can't possibly know what happens next.
More sanding
More painting. Here it begins to take on a clear direction. I consider this a "possibility", not a mandate. So I will go down this road a ways and see if it sticks, but I end up in the weeds, another possibility will be evident, I'm sure.
This is where the piece is at this point. I'll futz with it a bit and look again.
Hand sanding gives you more control over how much material you remove, so it's good for getting into smaller areas. Here is a video of me working on two different pieces:
