Transfer your mapped out drawing from your sketchbook to the watercolor paper.
When I first started working with watercolor I painted on hot pressed illustration board. I'd always run into the issue of making a sketch and not being able to transfer it. So I was left redrawing and being disappointed it didn't turn out the way the first sketch did. I went through many different ways of getting my drawings transferred.
The Tried Methods
Using the graphite transfer paper. Although it's useful for other projects, not necessarily for watercolor. Too much graphite muddies your paint.
Drawing sketches only on tracing paper, then rubbing the graphite onto the watercolor paper. I did this one the longest. I had to draw in reverse or allow the piece to be in reverse on the watercolor paper. How did I do this method? I'd draw on the tracing paper, then flip the pencil side onto the watercolor paper, and using a spoon, gently but firmly rubbed the pencil onto the paper. Although this method works, you end up exhausted and with lots of tracing paper to store/organize. Not easy.
Use a lightbox. It's a great idea, unfortunately if you're using 140lbs watercolor paper it's challenging to see through because of it's thickness.
Draw unplanned straight onto the watercolor paper. Going this route seems simple enough, yet if you erase too much you disturb the fibers of the paper which cause issues in painting. Also if you're a heavy handed drawer, your lines will create grooves in the paper and paint will get trapped in there. Then you'll have lines you don't want.
Blending the Methods
To be honest I switch from using the light box to drawing unplanned straight on the watercolor paper. It comes down to how much time I have, how much I want to plan, and also where I'm working (I move my work space A LOT throughout the year). In a sense, you can say I blend the methods.
Working With You
Instead of using the "Coral Hymns" piece I decided to use a piece that hasn't been transferred or painted yet. So we will go through this process together. Nice n' fresh. For this piece I used Maude (my favorite model) again, and it's the same reference I used for "Autumn". Only this time I flipped the image around. I also needed some kind of reference of someone holding a cat, and the main flowers will be chrysanthemums.
I made the sketch a couple years ago in a coffee shop, not thinking it would ever be a watercolor painting. Which means there's a lot of shading to ignore, and it will be a challenge to transfer. I'll explain more as I go.
Light Box
With one of my larger sales back in the day I decided to research and purchase a lightbox that could shine enough light through my watercolor paper. The one I own is the Gagne Porta-Trace LED light box. This was in like 2010 and there are a lot more options now a days, for probably a fraction of the price. If you're up to it, do some research. This Gagne is bulky and takes a 3 prong outlet (which my 1950's house has few of). Nonetheless, you'll want a light box that has some reviews of being able to light through thick papers. This is a tool you'll want to have, and a good one at that.
My lightbox is large enough to lay my sketchbook down with the page out. I don't need to rip it out! If it were a flatter light box, I could do this too without it being "large enough".
I tape the top and the sides to keep the paper from shifting. Then lay my watercolor paper on top, taping a hinge at the top so that I can lift and check if I need to. This also means your watercolor paper must be a loose piece, not attached to any pad or block.
I trace only the lines I want to keep and I don't fill in any of my "shading" from the sketch. I also try to draw lightly so that when I'm done I can easily correct anything that needs to be corrected.
Once I'm done, I take my kneaded eraser and roll it onto the drawing. This picks up any excess graphite and lightens the drawing.
After the Tracing
Look closely at the sketch and the transferred image. Notice how I didn't trace EVERYTHING. I left a lot to be drawn/painted later on. Not only will this keep the integrity of the sketch, but it'll keep some elements fresh. My ability to paint and draw flowers has changed since I did this sketch, so I made that decision to leave them open for now.
I then go in with my pencil, after lightening up with the eraser, and begin to add details I think I'll need before painting. This is using the method of just sketching straight onto the watercolor paper. I keep drawing lightly and once I know what I want, I lighten it with the eraser again.
Don't Over Work It
Finally, don't feel you need every, single, tiny, detail because you "might" forget it. You won't. And if you do, you didn't need it. I used to run into this all the time, worried I'd miss something while painting. It's a trap, and it will hold you back.
You can't literally control watercolor, only work with it. Leave some creative room for the medium and for yourself as you go. The drawing is the road map, the painting is the journey. Most journeys I've been on have detours and sightseeing. ;)
