This is certainly far from the only way of spotting a fake but as a rule of thumb they should not be magnetic. Silver and gold are non-magnetized, so take a strong magnet and hold it over the coin/item. If you feel a pull or if it sticks it is not genuine, it must contain some zinc, nickel or other filler. Local coin shows or antique shops usually have someone who is educated and willing to help for little to no cost.