The most important thing is to mentally move away from the complexity on the chart! What I witness with most candidates is that they "get drowned" in the chart, just looking at it in isolation and trying to come up with insights.
The most central questions to always ask yourself is: "What is the question we are trying to answer, which aspect towards answering this question are we now discussing, and what does this chart show that is relevant for this aspect?". Interestingly, I observe again and again that, as soon as the chart is presented to candidates, they oftentimes completely forget about what was discussed in the minute before getting the chart and what led to the interviewer handing it out.
So contextualizing the chart is the single most helpful habit that I would urgently advise to internalize. The "technical" reading of the chart is much less of an issue with most candidates.