We highlight a number of free online courses in our Lifehacker U series, but this free course from MIT on documentary photography and photojournalism is completely free, open to the public, and will teach you to improve your photography skills, even if you're not trying to catch a scoop.
Make no mistake, the course is an MIT class, and there'll be readings, assignments, and exercises to complete. However, the class is presented online in its entirety, and it's not instructor-led, so you can do it at your own pace and on your own time. The class is presented the way it was taught in 2009, so it's not necessarily new either, but the lessons you'll learn are timeless. Hit the link below to check it out and get started.
Documentary Photography and Photojournalism: Still Images of a World in Motion | MIT Open Courseware via Reframe