You can get/put ideas for what should be on the cheat sheet here.

Axioms of probability (finite spaces, infinite spaces)

Sequential and continuous probability models

Properties of probability laws

Conditional probability

Independence

Conditional Independence

Random Variables

Probability mass functions

Common random variables (Bernoulli, binomial, geometric) and how they come about

Functions of random variables

Mean and Variance, and their properties

Joint PMFs of more than one random variable