How to design a data structure ?

so I was solving Linked List problems on leetcode when I first came across this - 432. All O`one Data Structure, then this - [460. LFU Cache]

so I was solving Linked List problems on leetcode when I first came across this - 432. All O`one Data Structure, then this - 460. LFU Cache and then this - 1206. Design Skiplist apparently they all are about designing data structures, I tried problem 432 for a long time but failed and when I checked the solution, the dude had made some complicated nested datastructure using list, unordered set, struct ... now I hardly understood what he did, I couldn't imagine myself thinking about making such ds. but my question is - how do you think of a ds like that when you encounter any such question ? like how do you reverse engg. it or whatever ... ?