Devote five minutes to writing down everything you observe with your senses – all you can see, hear, feel, smell and taste – and another minute of what’s called kinaesthesia: how your shoulder knows you’ve got your head cocked to one side, the pressure between your knees where you’ve crossed them, the way the table-edge presses into your wrist.
Now, close your eyes and imagine your way into the setting of the genre fiction you have in mind – a historical time and place, another planet, or a crime scene. Don’t worry if you feel you don’t know it well yet, just let your imagination rip. Open your eyes and do exactly the same exercise for that time and place.