If you havn't got Dr Scott Persons book, then you should do so. It's sorta the Bible\" for this. I got mine off Amazon [latest edition] for less than $25.- shipped. If you look there, you might be able to find it even cheaper... however look for the latest version/edition.
Another good source is Dr Bob Beyfuss. A easy internet search will tun up lost of stuff from him. He's a authority on our favorite topic.