The biggest change that comes with the four stripes is a whole new kind of thinking. Everybody looks at you for solutions, be it fuel, missing pax, weather, MEL etc.
You can be a 10 hour FO, who knows all the procedures and systems, but it still does not make you a good commander (many of these know it all guys will really annoy you as many think that as they know everything, they are ready for command). I would suggest to focus on decision making, how it works. Eg. think about a simple failure (not like an engine fire, that is an easy one to solve:-) like ND2 fault or SEC3 fault after departure. Being a captain starts after you are finished with the ECAM. Everybody turns to you what to do next, return, continue or divert...
What I was told is that if you can change your thinking, you are halfway through an update. When you sit on the left seat alone, there will be noone to turn to for decisions. CRM is a good think, but it will be you who decides.
Good luck.