One of my more successful "do-overs" was a neutral toned landscape. I chose a reddish brown color to do the initial marbling, and then, as you can see in the images below, I rotated the painting to make it a vertical. Responding to what I saw on the paper, I composed a diagonal grouping of red tulips and did freehand painting using diluted washes of acrylic, making sure I varied my reds.
At the very end, I wasn't satisfied with the bright green leaf I'd painted in, so I collaged a piece of marbled paper onto that leaf shape and the piece was finished. I posted it on facebook and a client bought it right away! "Red Tulips and Green"; acrylic marbling/collage on paper, 10 x 14".