Very good topic. I think there are two ways to get the best advantage. 

Highroller: Pick a casino that has the best VIP offers. Casinos really appreciate highrollers, so you can really get good extra bonuses and offers if you stick with one site only. They also usually take really good care of you since you are a really valuable player so you get top-notch treatment. 

Average gambler: Use welcome bonuses to your advantage. This is the best offer that the casino will give you to get you to play on their site. Scout around and pick the best offers to maximise your odds. One problem with this is that casinos do not like it much. So if you only use welcome offers from many sister casinos, they can flag you as a “bonus abuser.”