~snip~
There are different strategies of promote. But in all of them the promoter have first of all to sit and to make research. He need to know who will play, the age of players, average bet, what games will be popular. After he get this information he can decide what advertise he need to choose - sometimes this is signature campaigns on crypto forums, sometimes social media, sometimes, may be TV. Different situations and different ways of advertise.
Researching before the promotion is very necessary because that is how they can find the right promotion for their casino. Most casinos will use methods that are almost the same as other casinos but what makes the difference maybe is the giving of bonuses to members because it will depend on how much money will be used to promote. Sometimes, casinos also run more than the 4 types of promotions you mentioned to attract more people who will become members. The strategy will work if they can find a suitable person to help them promote.
This is the easiest way as for me. In such situation the casinos will share the same users between them. But when you trying to attract other people, new gamblers - you ought to choose another way of promotion and create other marketing campaigns, unusual. The new casino have not so many ways to get gamblers - sign up bonuses, marketing, or new gamblers that didn`t gamble before.