I think I also submitted a PDF of a PowerPoint presentation I gave. That has a couple of different summaries collated from different papers, with lots of crossover.
I'll go through some of them very quickly: clear objectives, stable and long-term funding, being independent financially and technically, a simple interface and data upload, an opt-out model, concise data requirements and clean data that can be utilized and reported easily.
That's a perfect registry right there, if you can achieve that. There are well-documented guidelines for a good medical device registry.