syncing video to audio?

I am trying to arrange video clips to sync up with the audio/music file(for music video purposes). I am struggling with getting the clips to "lock" in place.

My goal is to get key/important clips locked in place, for example; each chorus(which happens three times) will have the same visual thing take place tightly synced up to the musical parts. I want to get those things locked down, then be able to add other things as I go with out the previosly layed down clips moving to the right, thus throwing all the clips to the right out of sync with the music. I am trying to lay out parts without having to fill up every second from left to right.

I am not sure if this makes sense without seeing what I'm talking about, I described the issue I am having in an effort to cut to the chase and see if any one has experience trying to approach editing in this way rather than adding music to a completed visual sequence.

Thank you!