I have two favorite ways to make a room memorable. One is to shoot for a theme. You can work on getting a living room that is just decorated with Star Wars homewares wall-to-wall or fill it to the brim with classy décor from a store like Papaya.com.au. The main thing to keep in mind is that if you are going to use a lot of decoration, it’s best to stick to a theme. Otherwise, you risk the room being memorable for the wrong reasons.
Another option I like is to keep the room relatively inoffensive. Pick one very bold decorative item to be the room’s anchor. For example, cover an entire wall with a massive landscape painting, get a giant print of a beautiful photo to hang on a wall, or just get one huge and incredibly intricate couch while leaving the rest of the room to have a minimalist feel.
These are my favorite methods because they are the easiest to get right. Of course, there are other ways to make a room striking, but those often require more finesse than an amateur like me can muster.