Academic databases contain the most reliable and up-to-date information: articles published in academic journals. However, databases are expensive to access, unless you are a university student. If you live near a university, you can access academic databases for free within the university library. You don't have to be a student to visit university libraries - you just can't check out any of the materials.
Google Scholar is a free database, but currently it does not contain very many sources.
If you don't have access to a university library, but you know the author's name, then sometimes you can find articles on a professor's personal website.
This is the best academic database, with access to hundreds of thousands of articles, but you will need to go to a university library to use it for free.
It's free, but many (if not most) articles are not fully available
It is not as good as JSTOR, but it is easier to use for novices; however, it also contains a lot of unreliable news media sources.
The World Library of Science (UNESCO & Nature)
This new database contains free articles and books on various topics in science.