When I did my first two Brick stitch squares, my canvas looked like this:

I had drawn my 25 squares and the surrounding borders and, other than leaving the center and one corner squares for last (per Ms. Slater's directions), my canvas was open to me.  It was also still flat.

My wrinkled canvas now looks like this:

I've filled in 14 of the 25 squares and I'm having to plan where I place my stitch samples and what colours I use.  My next stitch is the Hungarian Ground stitch so I want to make sure the three squares don't end up next to the Hungarian Point squares.  I also need a least one multiple colour square in the lower half to balance out the 3 in the upper half, but I also don't want to put a multi-colour square next to a multi-colour square.  If you count from left-to-right top-to-bottom, I think I'll be do multi-colour in square 18.  Stay tuned to how I work it out.