The delivery-form of the modules is already grounded in grey and ready to play. But with a little time and the knowledge of a simple painting-technics you can pimp your modules easily.
The painting-technics I use is called drybrushing.
You may ground your modules with a darker colour if you think the delivery-form may be too light-coloured.
The first colour I use (after the grounding) is a middle-grey.
Dip the brush into the colour and dry it with a tissue.
There are two rules with drybrushing:
You paint from dark to light colours, and the lighter the colour the dryer the brush should be.
Be careful to keep the coulour away from the metal of the brush.
It's harder to clean the brush when it's smudged that much with colour. And you may also spoil your paintjob by hitting the surface with the wet colour which has accumulated at the edge of the metal.
Hold the brush nearly horizontal and strike it over the surface of the module in the direction of the brush-hairs.
Now you only hit the higher parts of the module and the deeper parts remain dark.
After painting corridor and walls (don't forget the inner sides) with the first colour, I choose a light grey for the second colour and paint the module again with the same technics.
Keep in mind to dry the brush a bit more with the lighter colour.
The last colour is white which I only use for the edges and corners.
That's the last tweak.
You may paint the room with the same colours and technics but I prefer different colours and a chequer-board pattern.
Half of the tiles I paint in dark-blue.
Now I have to be careful the first time that I don't hit the walls or the other tiles.
For the tiles I also use drybrushing so I mix a light-blue for the highlights.
I drybrush the remainig tiles with a green colour that I get by mixing some yellow into the remaining blues on my pallet.
For the highlights I use yellow shaded with green.
With some routine you may colour a module within 10 minutes which enhances the look of it and gives it a personal touch.
We wish you a lot of fun with constructing and painting.