In order to reach the desired customer, a casino needs to do Promotion. Everyone has a different strategy to promote. There are a lot of casinos promoting social media right now, but the ones that I've seen the most are the casinos that have a lot of questions about their reputation. So they are spending a lot of money but not paying attention to the reputation buildup. If the reputation of a casino is bad, then spending money on promotion will not bring good results in the long run.
THe best practice is set up a budget and hire a marketing manager.
You can hire a freelancer too - and its good to keep changing them time to time - this brings in fresh change in the campaign.
Even if you hire the best manager, you will not get good results unless your casino is honest and attractive. Because of mismanagement, many casinos cannot be successful even if they spend a lot of money on promotions. In order to have a successful campaign, an experienced campaign manager must be able to bring you good results which you may not be able to do alone. So yes, hiring an experienced manager would be good to get good results from the promotion.