Position your desk so that you do not have your back to the door. This is the minimum feng shui requirement for the office desk. Be also mindful of not facing a wall while working at your desk. If you have to face the wall, use feng shui to make the wall "disappear" with vibrant images, beautiful art, etc; whatever brings a smile to your face and makes you breathe deeper and calmer.
Be mindful of the quality of air and the quality of light (natural and artificial) in your home office, as these are two of the good feng shui must-haves. If your brain is starving for oxygen and your body does not get enough natural light, you will not enjoy working there no matter how much you love your job. Consider investing in full-spectrum lights and do bring at least a couple of air-purifying plants into your home office.