Baobab72 - for entry to climb or descent Power, Attitude, Trim - for level off from climb, Attitude, Power, Trim.
For academic helicopter flying there will be a nominal climbing speed which will be different from the cruise speed so the entry to the climb is initiated with power (raise collective to achieve desired climbing power) the speed is adjusted with cyclic to achieve the required climbing speed and then the aircraft is trimmed.
For the level off the attitude is adjusted to accelerate towards cruise speed at approximately 10% of the RoC below the desired level off height, then as height and speed get towards the desired datums, the power is adjusted to cruise power and then the aircraft is trimmed.
In practise, the aircraft can be climbed at any speed (if you have the power) so PAT still applies - raising the collective causes the nose to pitch up slightly and vice versa when lowering the lever (due to the difference in V squared between the advancing and retreating sides of the disc) so even a cruise speed climb or descent will need some attitude correction with cyclic.
As you have probably discovered, moving one control in a helicopter means compensating with the other two and you will find yourself using your feet much more to maintain balanced flight.