I found this video on Reddit the other day. It features Damir Sagolj giving quick tips about photojournalism.
To me, the most important tip was to be invisible. When you're not invisible you're not able to capture the emotional moments of people. Now this doesn't mean go hide in a bush across the street and creep on someone. It's about comfort level, as soon as someone feels uncomfortable in a situation you lose all the emotion in the moment you're trying to capture. Emotion is essential in not just photojournalism but photography in general, it's what makes the picture tell a story.
Something that Sagolj didn't touch upon was what equipment/lenses do you use for pictures when on the job?
Sometimes as a journalist you don't have the luxury of walking up close to a subject and taking a picture, this is why a telephoto lens works best in most situations. A telephoto such as the Canon 70-200mm f/2.8L IS USM
or for Nikon users the Nikon 70-200mm f/2.8G AF-S VR II Zoom-Nikkor ED-IF
Both these lenses are quite pricey, ~$2300 each but definitely worth the performance you're going to get from these lenses. I personally am looking to buy the Canon version myself for sports photography mainly. I'll be sure to give a review once I get the lens!