Good sources are:
Three factors that have a significant effect on reliability are:
- Type of work (published book, blog post, unpublished journal entry, etc.).
- Author (university professor, recognized scholar, popular blogger, mega-church pastor, well-regarded rabbi, etc.).
- Publisher (academic press, popular pan-Christian/Jewish publisher, publisher associated with a specific religious tradition, website, blog, etc.).
Concerning the type of work, reliable works are published; that is, they are available to the public in some way. Your pastor/rabbi/professor's printed class notes/handouts are probably not reliable sources. However, if these same documents were posted publicly on a course website, they would be considered published for this site's purposes. If you have to post them online in order to cite them for your answer, they are probably not reliable (as we have no way of knowing if your pastor/rabbi/professor is actually the author and if he/she actually produced the documents). Academic works are generally more reliable than popular works, but this also depends on the author and publisher.
Reliable works are generally written by an author who has the reputation of being an expert by his or her colleagues/peers in the subject matter being written about. A Jewish scholar who is recognized as a Hebrew language expert by other experts in the Hebrew language would generally be a reliable source for information about the Hebrew language. An author is generally considered to be even more reliable when other experts still recognize him/her as an expert even though they may disagree with their research conclusions. An example would be Bart Ehrman, who is respected as a great scholar of biblical textual criticism by Daniel Wallace, another expert, despite significant disagreements between the two. Having a conflict of interest is generally thought to harm an author's reliability, but this is generally unavoidable in the field of biblical hermeneutics as many scholars are adherents of the religion(s) related to the biblical texts being studied (and even non-adherents are often considered to have a biased agenda). Even so, when a biblical scholar argues for the interpretation of a text that coincides with the beliefs of a specific religious tradition to which he or she belongs, it is usually best to also find a second scholar who supports this claim, preferably one who is not an adherent of the same religious tradition.
The publisher of a work has a great impact on its reliability. Academic, peer-reviewed journals and books are considered to be the most reliable sources (peer-reviewed by the wider academic community, not just by those who support the views of the journal). Publishers with a reputation for fact-checking are more reliable than those without it. Those with a conflict of interest are generally not considered reliable (for instance, a Lutheran publisher espousing a Lutheran interpretation of a text, or a Watchtower article supporting the translation choice of the New World Translation) unless substantiated by additional sources who do not have the same or similar conflict of interest (when possible). Self-published works are not considered to be reliable, including vanity press companies and any website with user-generated content (which includes others answers on the Stack Exchange network that are not substantiated by good sources).
A source is considered to be verifiable if readers can prove that it is reliable. An easy way to do this is to provide multiple good sources to support an assertion when possible. Granted, sometimes only one person has made a claim. But often a claim can be substantiated by multiple sources. This does not mean that multiple people cite your source. Numerous people can use the same source as justification of a false claim. The popularity of a source should not be confused with its reliability or verifiability.
Along with this idea: if no one can find the source anywhere, it may not exist. This doesn't mean that it has to be easy or free to access, but it should probably have at least been cited by others or discoverable in a public search of some kind.
Granted, this isn't Wikipedia and we do encourage the treatment of primary sources for biblical texts when possible. But this is mainly for the purpose of translation or determining the best reading of a text, not for making controversial original assertions. Original research should be kept to a minimum. If you're the only person who posits your hermeneutic method or interpretation, this isn't the forum for your new ideas. Go publish it in a reliable publication and submit to the process of peer-review by the wider academic/scholarly community. Otherwise be ready to provide some support for your methodology.
Yes, asking you to provide sources does make answering questions on this site more time-consuming. But taking the time to research what others have said and to back up your claims makes your answers more valuable to the users of this site and to those who find them via search engines. And you just might learn a thing or two, and perhaps challenge some false claims that you previously held.