It seems like an awful long time ago now, but in the WH Smiths sale, I bought myself a little box of Watercolour half pans. There's no particular reason I chose the Winsor and Newton "Cotman" sketcher's box, other than it being cheap (£8) at the time. There are similar products from Daler and Rowney (the Aquafine boxes) and other manufacturers.
They come like this;Which is at least part of the reason it took me so long to use it - the half pans are individually wrapped (very neatly), and I felt wary of tearing into them, for some reason :) Here's the closed box - it's on top of a Moleskine pocket reporter, for scale. (Don't use watercolour in the Moleskine though, it, and you, will not like it). It's a really nice size, and fairly readily pocketable, I think (although I don't carry it about). Here's the open kit. There are 12 half pans of paint, and travel brush (the brush handle comes apart, and the front end of the brush tucks into the rear, and you can see the closed brush in the first picture in this post. Think of it as the Kaweco Sport of paint brushes). The brush is a bit too small for large washes (it doesn't hold much water at all) but works on a small scale, or for detail. I'm mostly working on A6 size paper (slightly larger than Moleskine "Pocket" size) and it's occasionally too small for that! If I was carrying this around a lot, I'd get a water brush to go with it (Incidentally, whilst you're at that site, have a look at the author's DIY compact sketch kits, really nifty). At the moment, I just use my ordinary brushes - another sale buy - they shed hair like my dog does, unfortunately. Here's the first thing I did with it (don't look too closely, it's very much better from a distance) colouring an old sketch of a character from Lawrence Block's Matt Scudder books. By my reckoning, it's my fifth or sixth attempt at watercolour, and the first using "proper" paint rather than watercolour pencils.It's on A6 cheap sketching paper, so the washes are pretty light.
The paints mix nicely, and there's a good selection of colours in the box - I think I may swap one half pan for a black, or grey at some point. for £8 (I think they're £11 at full price) it's a decent way to experiment with watercolour, and more than adequate for my needs.