Hi Beth,
I have a registered HK business and we just got through our first year. I also just helped my business partner get his investment visa. Claire is right that you need to show self supporting evidence. However, the main thing actually for us was a good and thorough business plan. There wasn't so much 'actual' evidence, so to speak, and you're also allowed losses in the initial stages (first couple of years), but main thing is to show that you will not be a burden to the HK government and can bring something to the table. Hiring local, bring foreign business and contacts in, help to grow the local economy, etc.
Whoever you ask and where ever you go, you'll hear tons of different things, but probably best thing is to first evaluate your situation and how it pans out. Then next, a good business plan as it actually answers a lot of questions for you just writing it.
Good luck