There are many clues right in your own home or in the attics of your relatives. Bible records are an especially important source of information. They were usually, but not always, entered at the time of the event. Any kind of record or memento that puts your ancestor somewhere in time and place. Even these can contain human errors.
Primary sources are birth, baptismal, death and marriage records.
Secondary sources provide you with clues to researching your lineage. Your goal is to try and find as many primary sources of information as possible. Keep a log of your research so that you don't find yourself repeating research. The volume of information that you accumulate will grow very rapidly. Cite your sources by writing down the name, date and location of where you found the information.