Re: 🚀 WINZ.IO 🚀 GET FS TO TEST 🎁 UP TO 6 BTC BONUSES 🥇🥈🥉 €1000 SLOTS BATTLE
I know a simpler way: if the casino needed promotion, you could ask players to make a repost in one of the dozens of social networks, and for this give them a small bonus.
I didn't think about it before, I think this idea has a right to life. 
Keep in mind that spending on advertising should be minimal.