When I visited the V & A recently, I did a tiny watercolour sketch of my view as I ate lunch in the superlative cafe. It was a gloriously sunny day and the bits of the museum I could see in the courtyard through the tall windows was like a puzzle.
I always carry this mini childrens paint set with me for emergencies, and managed to create all the colours I wanted from it. I started with just paint, and then added some fine black lines for the detail.
* Reminder - I have an easy sketchbook class that you can take on Creativebug if you’d like an intro to carrying your sketchbook round with you everywhere like me :)