In addition to the use of palming(the practice of rubbing your hands together and then placing them over your eyes), a very helpful habit is the 20 20 20 eye rule. With this routine, every 20 minutes you focus your eyes on a spot at least 20 feet away for 20 seconds. Keep your eyes healthy with regular breaks from your computer, tablet, smartphone,etc.
Other techniques include:
Blinking more frequently as the time at our devices encourages less frequent blinking.
Putting your eyes through range of motion exercises several times a day(focus your eyes to each side, then up and down,etc.).
Massage your temples at least daily.
Eye Strain Prevention Mayo Clinic