In order to paint in the impressionistic style of watercolours that I prefer, a bold and confident approach is required. This causes problems for beginners, and even experienced painters if they have a break from working. Worrying too much about the process can lead to a cautious approach, which often produces a stiff and uninspired watercolour.
So what is needed is a way of relaxing, and almost letting the brush move without thinking. I expect that getting into a state of Zen meditation would be beneficial, but another way is to set out with a playful attitude. If you make up your mind, before you start, that you are going to work quickly and not try to produce a polished watercolour, then you can free yourself to just have fun. If the results are a mess, you have only spent a small amount of time, and you have probably learnt something in the process. If you find you like what you have produced, then you have a nice piece of artwork to keep. You might be surprised how often these pieces turn out to be some of the best. If you are a beginner, don't expect to produce a masterpiece, but working like this will help in your progress. Even playing around with colour-mixing on scraps of paper is a worthwhile exercise.
In order to be as carefree as possible, you can use the back of failed paintings to paint on. In this way you can use good quality paper, without the inhibition of a pristine sheet. In the exercise above, I used an old quarter sheet painting and divided it into four with masking tape. These little paintings were produced from memory with no pencil guidelines, just pure and free brush-work.