Keep it short
This ZEN advise might sound quiet paradox, however already in one of the letters in-between the acient authors Schiller and Goethe is written: “Sorry I had no time to keep it shorter”.
To be able to be precise and to keep thoughts and subsequent sentence short – you need to be clear in mind and feelings – and sometimes this need quiet some time. To pause – maybe even to mediate – and to sense along a thought or let emerge what’s coming in the very moment, leads you stepwise to this precise and clear state. Regularity helps to sink in, a certain practice as well, but what is mostly needed is a careful patience with yourself in order not to urgently longing for that clarity too much.