It's pretty easy to watercolour with markers and ink refills. You need some Staz-On, an Aqua Painter, and some Watercolour Paper.
1. Stamp your image onto your watercolour paper in Staz-On ink. You can use black, or any of the other colours they produce.
2. Colour the marker on the parts of your image that you would like to be darker. Use the Aqua Painter to blend the colour out to the rest of the image. You can always add some more marker if you want some parts a little darker.
3. For the reinker, you can squeeze a TINY drop out onto one of your stamp containers (or any other non-porous surface). A little goes a long way! Pick the ink up with your Aqua Painter, and colour your image with that. I have used a reinker in the Tangerine Tango colour, as Stampin' Up! does not produce Stampin' Write Markers in their In Color family.
4. This is my finished image.
5. Decorate and finish!