Here are my SOPs:
For town driving (at low speed):
1 I tend to just use the brakes to slow down or stop at traffic lights or junctions
2 I will change down if I am doing a Uturn and expect to accelerate after the Uturn
3 If I am driving an auto car, I leave the gear level at D
For downhill driving (e.g. Genting/Karak, Jelapang):
1 I will downshift to slow down and keep the car on low gear. This saves me from controlling throttle and brakes - not so smooth
2 On auto cars, I will shift down manually too
One other thing that I do is to use Dot 4 synthetic brake fluid. This will have a higher boiling point and will resist brake fade better.
For town driving (straight road), engine braking is not required hence when slowing down (just before reach junction and traffic light), just smooth foot braking will do. And for manual, depress clutch pedal only when you need to stop your vehicle (to prevent engine stalling when in gear) or downshifting (esp. when making U-turn and accelerate).
When descending (eg Genting), the most effective way to slow down is the combination between engine braking and foot braking. When i going downhill from Genting, the selection between 2 and 3rd gear was largely depends to the road contour (also depends to the weather coz sometimes it was foggy) and some foot braking (no need to step on throttle). Apart from engine braking, when approaching the bumps even from quite a distance, foot braking was applied earlier so that i can brake smoothly. Same technique applies to the automatic cars when going downhill ( selection between 'D3'/switch off 'OD' or '2')
However, when driving down from Genting, a short stop-by at Gohtong Jaya is a good idea to reduce (if not prevent) the chances of brake overheating/fade.