Don't underestimate paper and pencil or a white board.
It's easy to draw your first pass at the modeling, then build it in Neo4J and look at the results in either the Browser or Bloom.
Then, start refining the model. There are a lot of handy APOC functions that allow you to change the model en masse, so you can test out how the changes improve (or make worse) model.
The trick is to start with a sample data set that's not too big or too small.
