Sorry I know this is a very broad subject but how do you plan from the outset for scaling up your community?

I am using Snitz and MS access on a cheapo hosting plan (no sql databases, no ssl etc.). If things take off I know Access will not cope and I may need to swap to paid for community software.

What sould I be doing now when only 2 people have signed up (you know who you are, I thank you! to allow for the possibility of lots of members in the future?