Hints for topics to include:

Church Life:
Worship, committees, session/diaconate events, fellowship events (suppers, picnics, outings), special activities (guest speakers, special classes, etc.), community service, members, pastors, staff, and Sunday School activities.

Groups of the Congregation:
Youth, Presbyterian Men, Presbyterian Women, Clubs (bowling, ...), Music Program (choir/choirs)

Hints on where to find historical information:
Congregation records, especially session, deacons, and trustees' minutes, Annual reports, newsletters, special event bulletins

Presbytery records, Minutes of the General Assembly (for statistical information)

Local or regional histories, local newspapers