I have 5 different camera shots of the same event which is in lots of cuts that I need to sync up.
One thing that is annoying me is that when I drag a clip in the timeline to try and match it to the clip above it (which I have shrunk to 50% size to be able to see both clips) my playback window goes black so I its very difficult to work out how to sync them up without lots of trial and error.
Can anyone recommend a good technique for this kind of work?
You need to create multicam clips with the five angles.
Is there audio recorded on all five angles? If so, highlight the five angles in a bin, control click and select "create multicam source sequence" and then select audio for syncing. If all syncs correctly you'll end up with a multicam clip that you can use as a source clip in a timeline. Then map selecting multicam angles to your keyboard and you can easily switch angles in your timeline.
For more detail on this process, search out "creating multicam source sequences in Premiere" in a web search.