Equipment: Use a digital camera or the back camera of your smartphone to take high quality photos.
Background: Take the photo in front of a plain background such as white wall or screen. Make sure that there are no other objects in the background.
Lighting: Make sure there are no shadows on your face or on the background. Adjust the distance to the wall to remove shadows on the background. Face the light source such as a window to remove shadows on the face. You can use additional light source to get even lighting on the face.
Position the camera in the same height as the head.
Shoulders should be visible, and there should be enough space around the head for cropping the photo.
Head and shoulders facing the camera.