At this stage, your product, technical and audience research should be informing the development of your concept. You now need to make steps to develop this further. You should think about going on a location reccie - visiting potential locations, taking photographs and thinking about camera angles, framing, lines of action...
If you are going to have other people performing in your video, you will also need to take photos of them "in costume", whether as band members or part of your narrative.
You may also want to test out some effects or shot ideas in advance of storyboarding.
Also - keep documenting any other images/videos which are inspiring you.
Post, post and post again!