For scientific and technical writing, refer to the ACS Style Guide.
Citing and Referencing
If you do not reference a fact in your writing, assume that a critical thinker will give it low likely hood of being true.
When you quote someone, state their title and credentials. Give context to who they are to help your reader determine if the person being quoted is trustworthy and/or qualified.
Cite the page number when citing a book.
Avoid citing websites whenever possible. With the exception of a few online academic journals, assume that anything published online may be gone tomorrow and your reader will not be able to find it.
A website is not a journal. Before citing a website, try to locate a print citation.
Google is not a dictionary. If you cite a definition you got from Google, visit the "Google Dictionary" Wikipedia entry to discover who their current content provider is for definitions.
Google is not a book publisher. Books you find in Google Books, were published somewhere else. Check the title page.
Presenting Information
When you quote someone, always explain who they are. If they are an expert or researcher, state their qualifications and connect them to reputable organizations that sponsor their work. Doing this makes your writing more persuasive and makes it easier for your reader to research this person to come to their own conclusions.
Example: "Michael Kuhar, an addiction researcher at the Emory University School of Medicine, explains that..."
Give credit to the primary source of an idea, even if you encountered it in a secondary source. You should make an effort to read the primary source before quoting it's information and conclusion. If you are unable to, then be clear that you are repeating another author's interpretation of the primary source.