The first text I probably read was Patch Clamping: An Introductory Guide to Patch Clamp Electrophysiology by Areles Molleman. It is a very light text that will cover the basics.
For a deeper treatment Single-channel recording by Sakmann and Neher is a great reference to have for any electrophysiologist.
The Axon Guide, which can be found online as a pdf pretty easily on the molecular devices website, also gives a good overview of electrophysiology.
Molecular devices also has a number of webinars on different topics in electrophysiology that can provide some detail on particular aspects of the technique but they are often geared towards their own software suite (pclamp).
All three texts cover the basic set-up as well as different variations of the technique in varying degrees of detail.