One of the many ignorant actions are commiting Shirk, as well as Bid'ah.
In this article, you will learn what Shirk and Bid'ah are, and how to stay away from them.
Shirk is a type of sin. It is one of the major sins in Islam. It can mean many things, like associating partners with Allah (subhanahu wa ta'ala), which is polytheism (belief in multiple deities), and idol worship. If one was to die with these sins without repentance from them, he would not be forgiven for them, and thus will enter into Jahannam (hellfire).
To stay away from Shirk, do not worship anything other than Allah (subhanahu wa ta'ala), do not believe in polytheism, and only worship Allah alone without partners and believe in His oneness, and always fulfill Allah and His Messenger's obligations from authentic sources.
Bid'ah is innovation and misguidance. It is to make something in the religion that isn't actually part of the religion. An example of a Bid'ah is a fabricated Ahadith, to stay away from this, it is recommended to get Hadith from authentic sources like Sahih Al-Bukhari and Sahih Muslim, and also make sure it's chain of narration is authentic.
When you learn things that claim to be part of Islam, make sure to do research about it to make sure it came from an authentic source before believing in it. And when you come across Qur'an and Hadith quotes, make sure it mentions the source, If it does, go to the source and make sure the sayings are matched and true. If it does not, then it is recommended not to believe in the quote.
Shirk and Bid'ah are ongoing and one of the major sins in Islam, so it is important to stay cautious in what you believe.
May Allah bless you, and shukran.