Moguls are the lumps that are created when lots of skiers turn in the same or similar places, pushing the snow into piles. Moguls are not a set size they can vary greatly depending on snow conditions, sizes, spacings, steepnesses, and even patterns and shapes.
All adding to the difficulty of being able to ski moguls well. With large variations in moguls, this can make it hard to get into a rhythm or even know what to expect when skiing through moguls.
Because of the large variations, to be able to ski moguls well requires a lot of practice. You have to be able to deal with all types of moguls whether they are soft powdery moguls, hard icy moguls, or heavy slushy moguls. Then there is the variation in size, spacing and layout of the moguls, which means that each turn will be different.
Hard core mogul skiers use skis with a fairly large radius, which are quite stiff overall but with very soft and flexible tips. These allow them to get good grip on the snow when braking, but have the flexibility needed to get around the moguls.
If you are a beginner at moguls, The Green Line mogul skiing technique is the slowest and most controlled way to ski any mogul run. This mogul technique is where you both initiate and complete each turn on the flat top of a mogul and then “drift” (on soft edges with your skis perpendicular to the fall line) down the secondary fall lines and/or spines to the next flat mogul top that you have chosen as the spot where you plan to make your next turn. You can think of the Green Line mogul technique as skiing the flat mogul tops.
This video gives a technical view on the Green Line Mogul method.
This video is a skier demonstrating the Green Line Mogul method.