wet on wet leaves

I'm taking another online  class with Michelle Brown...Loosing up March...learning to paint wet-on-wet very loose.  This is my first attempt at painting these leaves.  Instead of drawing an outline of the leaves I used my paint brush loaded with color to define the leaf shapes.   Then I dropped in color, after color, until I got a desired color I could live with.  I was using my water brush and a small travel palette on non-watercolor paper.  There was some buckling.  When the painting was dry, I turned it over and on a low setting applied a warm iron to flatten out the paper.  I think in order for me to paint wet-on-wet I need to use a regular watercolor brush and my regular size watercolor palette.