Check for cemetery records with the church, sexton and/or funeral directors. Visit the cemetery and take a picture of the tombstone. Check the obituaries in that time frame.
General Land Office is now called Bureau of Land Management of the United States Department of Interior. Some federal land records are here, some in the National Archives and some are in state and university libraries. Public domain land states are largely available on the Bureau of Land Management, General Land Office-Eastern States free website.
Set up "proof files." These are your original documents that NEVER travel with you. Travel with copies if needed. Digital copies are easy to carry with you.
The National Genealogical Society, Washington, D.C. has a genealogical course available for national accredation and sells both supplies and reprinted genealogies and other books.
Decedent refers to the deceased person.