It is extremely important for you to keep track of where you found your information. This is called citing your sources and it serves a number of purposes. Firstly, it acknowledges the work of others. Secondly, it provides a method for you to check back on information at a later date which is particularly useful if you come across conflicting information from a different source. Finally, it demonstrates a level of effort that other researchers will respect, since it provides them an opportunity to verify a piece of information for themselves. You may spend years compiling information about your own family, only to have it discarded by others as hearsay because the sources have not been properly documented.
Citations are most useful if they follow a recognized convention. This also lends further credibility to your research. Numerous authors have written books or online articles to serve as guides to assist you such as:
Cite your sources: A manual for documenting family histories and genealogical records
by Richard S. Lackey, F.A.S.G.
John Wylie, How to Cite Sources
FamilySearch “Cite Your Sources”