There is so many common black hat techniques which people try to do and in the end, their sites get penalized. Let me aware you from few of them.
Don’t try to create low-quality fake backlinks to get rank higher.
Don’t try to copy the content of other websites for your site.
Never copy the graphics of another website.
Never try to mislead your audience to bring them to your website.
Note:- Basically, be honest with your content and site quality. Google’s artificial intelligence is much stronger than your imagination. So, never try to cheat people or other search engines.