Some pointers:
(1) When we are reading the data set, our job is simply to understand what is given. I dont think it is useful to over-analyze the data at this stage. Do everything possible to understand what the given data is. Analysis - as per the question.
(2) Read the question and given statements if any super carefully (applies to all, but also for calculation heavy data sets, where one wrong turn can waste a lot of time). Re-read once if even slightly unsure.
(3) In most cases, quick calculations and approximations are better than using the calculator.
(4) Often, in these questions, if a certain type/pattern of calculation is needed for, say, a Q1 Statement 1, the same calculation may be used again in a later statement/question.
So,
-> Write neatly enough that you can refer back to how you calculated something as needed
-> Once you identify that the same calculation scheme is being repeated, make that process as easy to iterate as possible.
For example,
A particular calculation involves taking an value Y and then doing Y x (200/3000) x 45.
And when you see that the same calculation has to be done for multiple Y values, dont do Y x (200/3000) x 45 again and again. Just figure out once and for all that this is basically 3Y. And so, just do 3Y every time.
Such things sound silly perhaps, but it could help!