You don't have to do anything if a person has brief periods of staring or shaking of the limbs. If someone has the kind of seizure that produces a dazed state and automatic behavior, the best thing to do is:
Watch the person carefully and explain to others what is happening. Often people who don't recognize this kind of behavior as a seizure think that the dazed person is drunk or on drugs.
Speak quietly and calmly in a friendly way.
Guide the person gently away from any danger, such as a steep flight of steps, a busy highway, or a hot stove. Don't grab hold, however, unless some immediate danger threatens. People having this kind of seizure are on "automatic pilot" so far as their movements are concerned. Instinct may make them struggle or lash out at the person who is trying to hold them.
Stay with the person until full consciousness returns, and offer help in returning home.