how can I make this look (the Holga look) my own, and not like so many others out there?
I would suggest you can’t, as with any camera, lens, equipment or process technique. Because someone else can always use the same combination of above to produce a similar look, although I can understand the combinations of these are almost limitless and many people wish to experiment, which is fine. Some quite famous photographers also use specific techniques/camera/lens/lighting/etc. to help identify and signature their imagery. However, without wishing to preach, I believe that personal vision is developed over a long time to make that look your own. To use an analogy if you spend most of your life carving wood and making furniture you may become another Thomas Chippendale, but with your own look (nothing to do with the chisel you used).