And you have instant colour. This type of ink bleeds out giving beautiful shades of blue and grey. I've also added a line of yellow ink down one side to suggest shading.
If you actually dip your paintbrush into ink* rather than water to begin with then you can achieve all sorts of interesting coloured effects.
Such as this... which I think takes the fear out of making a coloured drawing. It would be good fun to repeat this exercise using some really whacky colour combinations.
Or of course you could just fill up the page with colour. Whatever you try it doesn't matter. Remember you are not trying to make perfect drawings or beautiful works of art, you are experimenting and you are trying to generate ideas... keep pushing boundaries and see what you come up with. You might surprise yourself.
*I've used Kohinoor ink palettes to add colour to these drawings - available from ArtVanGo