Unless you really like having to do your research more than once, it is important to keep track of where you find all of your information.
Document and cite those genealogy sources, including the name of the source, its location and the date. It's also helpful to make a copy of the original document or record or, alternatively, an
abstract or transcription. Right now you may think you have no need to ever go back to that source, but that probably isn't true. So often, genealogists find that they overlooked something important the first time they looked at a document and need to go back to it. Write down the source for every bit of information you collect, whether it be a family member, Web site, book, photograph or tombstone. Be sure to include the location for the source so that you or other family historians can reference it again if need be. Documenting your research is sort of like leaving a breadcrumb trail for others to follow - allowing them to judge your family tree
connections and conclusions for themselves. It also makes it easier for you to remember what you've already done, or go back to a source when you find new evidence which appears to conflict with your conclusions.