>>3590524Shutter speed and aperture are the settings that influence what kind of picture you take whereas ISO is normally changed to help you use the aperture/shutter you want. For example, if you're in low light and the shutter speed gets too slow for you to take a steady shot, you would up the ISO to let you speed the shutter up enough.
There's no artistic trade-offs with ISO (just good quality to bad quality) so I would leave it on auto while you use shutter and aperture priority modes to learn how they work. Unless your pictures get too noisy, in which case, set it low when the light levels are bright enough.
