There are a lot of ways you can do this, one of which is to remember to keep citing sources and giving credit where credit is due. As plagiarism is the act of stealing or not acknowledging other people for the work they have done, giving credit using a references tab or just directly saying it was from someone can be one way to avoid committing plagiarism.

Another way is to make sure that you are quoting and paraphrasing correctly. You can avoid unintentionally plagiarizing in quoting by making sure that the text you are taking is enclosed between two quotation marks and putting an in-text citation or text that showcases who wrote that line. For paraphrasing this time, make sure to not only switch the order of the words but also the words in the text with their synonyms. When paraphrasing properly, you have to fully rewrite the original sentence in the way you understand it.

The last way that will be described here is to just directly use a plagiarism checker before submitting a work or posting something. As plagiarism checkers are the most surefire way of checking whether your work has parts that are plagiarized, this is definitely one of the best ways to avoid unintentional plagiarism. On these sites, they even tell which parts of the text contain plagiarism, so those who use them can easily locate the plagiarized parts and replace them accordingly.