You would probably get some better advice if you list the company you have scored an interview with. There is bound to be someone on here that will give you some advice.
However, from my limited experience,
You normally only have one interview, which in normally two people, one asking technical questions, the other asking CRM and general personality stuff. The technical part of the interview has never been anything too taxing, but make sure you know something of the current type you fly (even if it's a cessna) as they invariably ask you to describe either the fuel, hydraulic, electrical system. It also helps to research a bit on the company you want to work for (history, who own them, who runs them, aircraft, bases, etc) and also research something on the type you are hoping to grab a seat on (ceiling, max speed, engines spec, max tow).
A psychometric test, if required, is performed before or after the interview depending on time. However, the interview and psychometric are normally done on the some day.
If you are successful, then you get called for a sim assessment. They will send you a brief of the profile long before you will be required to fly the sim. Some people spend hours on flight sim perfecting the profile before the sim day, but it depends on your confidence, as what they are mainly looking for is that you will not be a training risk during the type rating.
After that comes a nice letter with a start date. Good luck and if you post the airline I'm sure someone will come on with some specific advice.