Festivals are big, chaotic, busy events. That’s sort of the point. But it means that if you show up to the festival unprepared, then you are going to have a hard time getting good photos. Unless your plan is to just shoot over the crowd with your iPhone, it’s important that you do research.
Getting some information in advance shouldn’t be too hard, because festival are also always organized by someone. You will often be able to find the location and timing of key events by checking out the website or reading reviews of last year’s festival. If you can’t find what you looking for, consider getting in touch with the organizers. Especially if you have media credentials, they should be able to provide you with an itinerary and maybe some tips for where to set up.