Here is a very good article on the principles of interpreting scripture. It includes the chart I used in the service.
Bible Interpretation in a Nutshell
Bible Interpretation in a Nutshell
Here's a good guide from Theopedia.com.
An important concept in interpretation is exegesis vs. eisegesis. These terms are defined and explained here. (In general, exegesis means we allow the text to speak for itself. Eisegesis means we make it say what we want it to say.)