The best way is to use a pair of binoculars or a telescope, and place a piece of white paper behind the focus of the lens so that the disk of the sun is projected through the eyepiece onto the paper. With most telescopes, you need to cover the entire front aperture of the telescope, and cut a 1-inch diameter opening to let the sunlight through the optical system. This method is good enough to let you see most sunspots and eclipses in perfect safety. You will not see sunspots unless you use a telescope of relatively good quality since typical sunspots are only a fraction of an arc minute in size.
Other viewing methods involve placing a filter in the eyepiece and viewing the sun disk directly. I am, personally, very squeamish about doing this because infrared radiation is not very easily blocked this way and filters are often rated by how much optical light they block, not infrared. Your retina can still get 'toasted' if the infrared levels are too high, and you won't even notice the retinal damage has been done until later on when other conditions start to manifest themselves perhaps weeks or months later.