PAT Power, Attitude, Trim. as has been said, for everything i.e. starting a descent, levelling off after a descent, starting a climb EXCEPT levelling off after a climb, when it's APT.
Think about how you would use the power ( accelerator ) in a car to maintain a constant road speed up and down a series of hills.
Do nothing in a hurry, make a small change and wait, don't 'chase' airspeed or height - get the attitude right.
Find a rivet, or corner of the windscreen, that matches the horizon in a turn, and look ahead of the nose in the direction of turn, but out of the corner of your eye see the rivet you have picked and pull it towards where your eyes are looking - couse, you'll need a different rivet - or whatever - for left and right turns ! Relax your iron grip on the control column.