I highly recommend any of Dave Spaulding’s material.
Keep in mind that your method of carry needs to be one in which you can easily access the gun or other weapon fro a seated position under stress and in a short time frame. Practice it dry in your garage in the car to get good with it.
- Configuring Your Snub Nosed Revolver for Concealed Carry (gunsafetyblog.com)
- Transitioning to the Backup Gun (gunsafetyblog.com)