Here’s a simple example of how to transfer an original sketch onto watercolor paper. Create your sketch on tracing paper in pencil. I used a thick soft pencil. My sketch is of a seed pod I noticed when I came out of a store this afternoon. It was hanging off a tree that was next to my car in the parking lot, and the red tip caught my eye. I thought it was interesting and plucked it up. I only did one simple sketch. My sketch is intended for surface design, and for that, realism is not key here, but rather simplified silhouette and a pleasing shape for a pattern.
Once I had the initial sketch on the tracing paper, I placed the paper upside down on top of a piece of watercolor paper. On the side of the tracing paper without the drawing, I used a bone tool to rub the drawing off the tracing paper and onto the watercolor paper. You can use the back of a spoon. Using tracing paper is helpful because you can see through it and look at the design as it is forming on the paper, and decide where you want to place elements.
The rubbing comes off the paper and creates almost a stamp effect on the paper. You can rub out several more of your motifs onto the paper before needed to go back over the drawing with graphite so that it’s fresh again for additional transfers.
After creating an arrangement of my seed pod things (if anyone know what kind of a tree this is from, please do tell!), I then took out my watercolor paints and proceeded to “color.” I used only two colors – ochre, red, and a touch of white at the end. After painting the ochre and red, when all was dry, I erased the pencil marks, but because I used a lot of graphite and made heavy imprints, the marks were not thoroughly removed behind the ochre and red. In the red, I liked the graphite giving a little burnished look so I didn’t have to paint in shadows. Doing this differently, for a cleaner more professional look, I’d make the motif larger, use less graphite and lighter “stamps”/impressions, and paint using gouache inside the lines so they could be easily erased.