What are some black hat SEO practices to avoid?

Focus on two or three black hat SEO practices that you avoid. Explain why the practices you discuss should be avoided.

"I feel that keyword stuffing, especially using hidden text, is one of the most important black hat practices to avoid. The goal of SEO is to generate organic traffic legitimately, not by tricking the system. Link schemes are another practice I avoid. While it can be challenging and time-consuming, links should be earned, not paid or automated."