Overview of the Two Kinds of Epistles
Paul wrote his 13 letters beginning with Romans and ending with Philemon. The first nine letters were written to seven churches that Paul had either founded or took a personal interest in while on his missionary journeys. Here is a map of the location of these churches:
The Travel Areas of the Acts of the Apostles; also where Paul Sent his Letters
(city names in "stamped envelopes", the one province "unstamped")
Used by Permission: http://www.ccel.org/bible/phillips/JBPhillips.htm
Following this, two letters (one in two parts), often referred to as the Pastoral Epistles, were written to encourage two pastors, Timothy in Ephesus and Titus in Crete; and one letter was written to appeal to a coworker, Philemon, to forgive his wayward servant.
We are not sure who wrote the letter to the Hebrews, but the remaining epistles are titled after their authors: James, Peter, John, and Jude.
While we often read things semi-chronologically in the Bible Book Club, I did not want to break up the fast-paced narrative of Acts. Chronologies vary but here is a proposed timeline for where the epistles fit in the events in Acts and beyond: