Writing code to simulate a simple problem has helped me. Also, sketching out a problem by hand. I found this book a fun introduction to simulating some basic ideas: Probability, Decisions and Games: A Gentle Introduction using R https://www.amazon.com/dp/1119302609/ref=cm_sw_r_cp_api_glt_fabc_9A2ZWB4RPNEEHSYA4WTX
https://www.amazon.com/Probability-Decisions-Games-Gentle-Introduction/dp/1119302609/
https://www.amazon.com/gp/product/1138393290/
i always buy used versions from amazon
always save money and have never been disappointed