Each casino has also to find its own way, because not all customer types will behave in the same manner. If you are going for the masses, you would need to provide a decent service at an affordable price, but if you are whale hunting the focus should be in help, service, usability,... the moment a whale perceives that there is commercial pressure or any sign of untrustworthiness the site is done.
Every casino has different behavior to attract the interest of gamblers, actually the focus for service, assistance, usability should be maximized for all active gamblers and not just for whale account hunting. But before advertising a gambling platform, make sure the casino has interesting games and fair games, customer service must be quick to respond when there are reports from users.
Every single casino has their own way of promoting their sites some of them used social media such us facebook, youtube or even in to Twitter to promote their casino and some of them used forum like what other did here they run for a signature campaign but only thing to advertise your casino is based on the their performance how they handle some issues how they handle thier customer etc.