I had to revise part of the image before I had the go-ahead for final so I pieced it together in photoshop, nudged a few other elements until the composition worked and allowed room for the call-out type. I had scanned it at 600dpi (Epson Perfection V500 for the geeks out there). Once I opened it in Photoshop (again, Geeks - an elderly CS5 on a Mac Power PC OS5, Wacom tablet) I hit command-L (or Image-->Adjustment-->Levels). In the dialog box I select the white eyedropper, set white point as:
I touch it to the sketch in a grayish area and that will set that as my lightest point. I play around with it a lot, select the black eyedropper, set black point and touch that to a dark point on the sketch, move the gray slider on Input Levels until I like the balance. Hit okay. I like to convert it to grayscale at this point also.
After that I clean up the sketch using my favorite sandy textured brush. It is not essential that it is perfect - I continue to tweak that layer throughout. At this point I change the image size to 400DPI.
Now double click on the background layer:
when the New Layer dialog box comes up I rename it "Line" and change the mode to multiply:
With me so far? Now you have your line on an editable transparent layer. Next I add two layers below the line layer. One I name Background and fill with white (or sometimes a color or texture or gradient, but to keep it simple we'll go with white now). The other layer I change to multiply (I always name these Multi). Now I get out my good sandy brush and do some quick value block-in on the multiply layer. Like so:
Now I convert it back to RGB, when it asks me if I want to merge layers I say hells no. Now I hit command-U (Image-->Adjustment-->Hue/Saturation). Check the Colorize box:
I play around with the sliders until I get a color I like - sepia is typical for me. Ho-hum. The good news is that now I am ready to put some color on it. I make a new layer directly under the line layer and name it "Color" With the sandy brush again I start to block in my color:
I continue to add color on various layers, block in some color on that long neglected background layer:
I am extremely layer-happy - I typically use thirty or more layers on an image although I try to merge them when I can. I might put a texture or some details on a layer above another to keep from disturbing the layer beneath - I use the eraser tool set to the same sandy brush to clean up as I go.
Now I change the image to my final size - usually 300 dpi, change to CMYK if it is for print (sometimes this is a bit panicky when I realize I've been using colors out of gamut, good thing I left it in layers first!). Now I save as a layered file (for revising if needed), then Layer--> Flatten, resave as image name/flat.
A few other pieces I've done for Highlights in this method recently:
Highlights For Children, April 2012
Highlights For Children, May 2012