I will start by reviewing which group are already operating successful in DC. Even attend a meeting or two. This will give you a better knowledge/understanding of what's on offer. The key benefits they provide for their members. If there is anything missing or something that you can add. For people to join a new group and show up regularly there most be clear benefits for them to see and understand from the out set. Networking is all about Building Relationship and it takes a long time and effort to be fruitful at it. I hope this is helpful.