I learned about retrosynthesis from Clayden's Organic Chemistry..if you can get the book there is a chapter devoted to the basic principles of retrosynthetic analysis... afterwards you just have to exercise...There is also a book only about retrosynthesis, written by Warren..Forgot what the actual title is. However, it seems a little old but I found it pretty helpful in gaining all kinds of perspectives about how you can create a synthesis. Hope it will help you too.
I'm not sure if I caught the retrosynthesis. Maybe the follows?
Inverse synthetic analysis method from the molecular structure of synthetic product, using the method of "cut off a kind of chemical", this method is cutting off a key molecules, make the molecules into a likely to get a method of raw material. Synthon was cut off by fragments of the molecular bonds, usually with one ions. Thus obtained can be in the process of synthesis of less complex assembly structure unit. Among them, the most main is Disconnection and Sython these two concepts.