1. Original Content
2. Get your members to post links of your original content on other sites. This is different than a link exchange, exchanges do you no good. Your looking for non-reciprocating links. For example, if your site url was active on this page then it would count as a link to your site and thus you would have your first one.
3. Submit a sitemap.xml file to google. You do this by create a sitemap.xml and then giving the direct link to google so the bot can see all your pages and you then get scheduled by the google bots to peruse your site.
4. Make sure your site is open to the bots, if you have a full lock down on your menu then you'll hide 99% of your site from the bots and that will only hurt you, not help you.
5. Open additional sites and try to create some linkage between them. Be careful though, you don't want to end up with reciprocating links as that will only hurt you. Word to the wise, don't place these sites on the same server, the bots will pick that up from the IP's & NS1/2's.
good luck