Bad programmers worry about the code. Good programmers worry about data structures and their relationships.

git actually has a simple design, with stable and reasonably well-documented data structures. In fact, I'm a huge proponent of designing your code around the data, rather than the other way around, and I think it's one of the reasons git has been fairly successful

The actionable tip here is to start with the data. Try to reduce code complexity through stricter types on your interfaces or databases. Spend extra time thinking through the data structures ahead of time.