What was the basic approach Mendel took to studying inheritance patterns?

What was the basic approach Mendel took to studying inheritance patterns? What organism did he use? What characteristics make it a good model to study genetics? What is a true-breeding/purebred organism? What is self-fertilization? How is it different from cross-fertilization? What is the F1 generation? The F2? What were Mendel’s three main conclusions from his monohybrid experiments and how do they translate into what we know about genetics today?