I used Cadmium Red (hue) artist's acrylic paint for the letters and Process Black for the strips in between the boards.
I didn't know I was going to paint anything at the beginning! I chose my colours after experimenting quite a bit on an offcut of wood, and that's what I strongly advise you to do too.
Finish: I finished the whole surface with an 'oil-wax' preparation that doesn't affect the wood colour. Put 'oil-wax' into a search engine and you'll find many similar products that will give a clear, polished finish. I really didn't like the idea of a shiny surface - even beeswax could be too much. Alternatively you could use an artist's matt acrylic varnish with U-V inhibitors; you can find this in most artist supply stores.