2. Proper posture
When you are sitting, your back should always have the support and your feet should be kept on the ground. It is important to choose a seat with good lower back support, armrests, and a swivel base. You can use a book or a small box and slightly elevate your legs to reduce the pressure on your spine from sitting for a long period.
If your work involves standing for too long, then try to place one foot on a stool from time to time. This will help one of your legs to rest while the other one continues to work so that your risk of suffering from sciatica will decrease.