• Birth, Marriage and Death certificates
• Baptismal certificates
• Wills and testaments
• News clippings. Journals and other magazines that relatives may have written for, or been written about. This includes amateur publications such as church or society newsletters, based on what your relatives were involved in.
• Photographs. These have an article all of their own
• Military service records and medals
• School.university, and other educational certificates and awards
• Business and other occupational documents, and trade union records
• Diaries. Hope that these are not written in indecipherable code, such as my mother-in-law used. It was her own private version of Pitman shorthand. But we picked out a few names and dates!
• Letters and postcards - kept by anyone in the family tree.
• Tape recordings; film or video recordings
• Books and other items with inscriptions or dedications: check the fly-leaf!
  

There are many more possible sources, depending on the family background. Use your imagination, and ask your relatives for help.