Ok, I am new to the vB team, but I come from administrating a large vBulletin forum (~550,000 users) for the last 5 or so years, and in the past 2 years I have managed Internet Brands Automotive forums (approx 90 forums, some of which the largest forums out there). I thought I might do a series of blogs outlining some suggestions based on my experience which hopefully you might find helpful in expanding and growing your forum. I will start with just some basic tips/tricks, and if you find this useful, I can make some more posts and can even get into more of "heavy stuff" including the theory behind it for those that might be interested.
I will add a caveat, guiding a community is an "art form", not a science, my suggestions and advice should be used as such, there is no "cookie-cutter" approach that works, it is a lot of slow and often tedious work, but done right it can be incredibly effective to build your site/brand.

Users are your customers - keep in mind, every user that comes to your site is your customer. Even if they may not be paying you any money directly, at all times treat them as a customer, with respect, humility and "good grace".

Surround yourself with the right people - I think this applies in life as well, but on a forum, ensure you have the right people moderating/administrating it for you. Look for honesty, integrity and transparency above all else, with communication skills following shortly after. "Popularity" can be a hit and miss attribute when seeking people for leadership positions. Try to understand what they are seeking from the position too, so you can tailor it for them.

Participate - the best forums in the world are driven by a common passion. Don't be afraid to share yours.

Communicate, communicate, communicate - changing the font in your header? Adjusting your terms of service? Bringing on a new moderator? Scratching your nose? Don't be afraid to let your users know, even if they don't respond, doesn't mean they don't care.

Make it fun - doesn't matter how much a user is making you tear your hair out, take a step back before responding, everyone comes to a site for some form of enjoyment, doesn't matter what the question is, don't be afraid to dim the lights, crank up the Bon Jovi and make them enjoy it.

Integrate, don't alienate! - less on the rules for newbs, more on the feeling of making it a well worn comfy lounge chair for all. Doesn't matter the level of participation of a user/lurker, be welcoming and thankful for it.

Ban Stick - use as an absolute last resort. If you have to ban anyone, see it as a failure on your behalf to successfully integrate them in your community (and subsequently review your approach as to how you and your leadership go about welcoming/integrating users), not a failure of the users to understand the rules.

Be flexible - rules are great, they are necessary, but always put in context the level of the infraction, moderation can beget moderation

Part 2