Use a computer for no more than 3 hours a day.
Can't use the computer in dark place.
For prolonged use, it's best to add a separate monitor and keyboard. The laptop can be planced on books so the top of the screen is at eye level, then use an external keyboard so that your elbows can rest at 90° by your side.
Keep a distance of 30 cm from the computer.
Use a computer for 1 hour each time.