AP Statistics is the AP course students most often describe as not feeling like mathematics, and the observation is correct. In calculus you derive formulas and compute; in statistics you interpret data, build an argument and reason under uncertainty.
That difference means the study method has to be different too.
Why it is a different kind of AP
In most AP mathematics courses there is one right answer. In AP Statistics, a correct answer to a free response question does not receive full marks unless it is supported by correct reasoning.
The College Board scoring rubrics draw a clear line between writing the right number and demonstrating the right statistical reasoning. So one habit has to form early: write every answer together with why.
The four blocks, in order
Exploring data, covering univariate and bivariate analysis, distributions, correlation and regression.
Sampling and experimental design, covering sampling methods, experimental design and sources of bias.
Probability, covering probability rules, random variables, and the binomial and normal distributions.
Statistical inference, covering confidence intervals and hypothesis tests. This is the heaviest block and the one that generates the most questions.
Many students enter the fourth block unprepared, because the first three look easier and get underestimated. Every technique in inference rests on concepts from the earlier blocks; without a secure foundation, hypothesis testing turns into memorisation.
The three most common mistakes
Using terminology loosely. Confusing population with sample, or treating correlation and causation as the same thing, loses marks directly against the rubric.
Skipping the context. A result has to be placed in the context of the question, not just stated as a number. A low p value therefore we reject is not enough; what that p value means in this context has to be answered.
Not practising graph reading. A large part of the exam requires correct interpretation of a given graph, and that skill comes only from working through many of them.
Free response strategy
There are six questions and the time is tight. The biggest mistake is spending too long on the first question and never reaching the harder ones at the end.
A better approach is to scan all the questions at the start and begin with the one you feel most comfortable with. Show every step, because partial credit comes from those steps.
Who it suits
Students heading for the social sciences, medicine, biology, economics or business, where statistical reasoning is used constantly. It also pairs naturally with AP Psychology, whose research methods section overlaps with it directly.