Airbus has so many tools... Use them any time you see it fit to use them. If you are the Pilot Flying you have to fly the airplane. That can be full managed, almost full managed, partially managed, selected, AP OFF... As required by the situation and according to circumstances. You must never be flown by the airplane. Ignore those who tell you to manage everything every time.
If you don't like the V/S of your airplane, or the rate at which it is losing or gaining knots, or the rate at which it is pitching, or something, you are the pilot flying and have to make the airplane do what you want it to do.
For the time being, get familiar with the machine, understand it. Then study it again and you will see you didn't understand it so well, so study it again and understand it. Still, you have to study it a bit more... Learn from others, but always in a critical way (don't learn bad habits) and beware of negative training (lots of it can be poured into you if you are unlucky with the TRI, TREs...). With time, experience and a constant learning mentality, you will reach higher and higher levels of understanding and you will truly master the machine. Enjoy the process. After 10 years I still learn and I am sure there are still a few levels to reach.