To start with, you need to have an idea which of the many different casino games that you might be interested in. For instance, if you are interested in casino poker and blackjack you will want to choose an online casino which has both of these games available to play. Obviously the majority of casinos which are online will have these games, so you will not have to look too hard for these.
Perhaps you are somebody who prefers to play slot machines? If this is the case you need to find a casino that has a large range of different casino slots on offer. Some of the casinos which are online have a huge choice of different slot machines available to play. So if you're really keen on these opt for one that has plenty to choose from and you will be kept happy for a very long time.