I'm kind ofnew at this myself,but one great source is relatives that maybe you haven't been in touch with for years.My cousins have picturers and letterr and such that I of course never knew about.what a treasure trove of iinfo they can be.
IN fact,one cousin had my grandfather's family bibile ! The names and dates in there sure were a help..for instance,having middle names is a HUGE help in online searches,and dates are a bonus to that.Even just a middle initial is a big help on a search engine.
also,I have found some very interesting things just by Googling a person's name. You just never know where the next bit of info may pop up from.