I would agree with Steerpike here, however sometimes not having a vision and just filming can result in good stuff. After all, isn't that how most Documentaries are made?
Having a vision and an idea can be great, but I think the best thing that will help you here, as noted in Steerpike's thread, is to have an eye for cinematography. That will improve your videos immensely. Don't just plop a tripod anywhere - find a location that looks visually interesting on camera, then start shooting.
Some of my favorite videos I've
made, or at least the ones I'm personally most proud of, have come from me just picking up a camera and a deck, and randomly travelling across LA, or my school campus, and shooting where I think looks cool. Didn't have a specific idea, just shot in places I though looked interesting, and then in the editing room it all came into something I really liked.
Lastly, one piece of advice I think is vital from Tobias Levin, is to always be making videos. Even if you don't love it, post it. The more videos you make, the quicker you get better. So keep being persistant, and good luck