We are planning to launch signature campaigns as well as other stuff, like paid ads, affiliates, social media activity etc. But it's not the idea of this topic.
Signature campaign works best for casino and many will be willing to wear your signature for even zero pay if they can include their referral url in signature and you have nice affiliate reward.
Buying ad space on this forum is also best way to advertise as this forum is full of bitcoin users and many of them also gamble.
Asking authors of different bitcoin gambling related news site or review site to post paid review about your casino can also be helpful.
Twitter and facebook giveaway for sharing your stories or posting about your casino can also attract many new users.