There are many different ways to use line breeding effectively. If you really get into the most successful award winning breeders lines. You will find that they all use a form of line breeding. I don't know of any special type of line breeding that is most effective for everyone, as far as a brother to sister, or father to daughter, or half brother to half sister, or grand daughter to grand father, sometimes it might work but not as a general rule for everyone. From my experience it's about understanding the traits and qualities that each line carries and then line breeding those traits to set them in deeper to the offspring. For example, I like to select a female with my good blue color line and breed it to a male out of my size line, then I take the offspring back to the blue color line, and then take that offspring back to the big size line again, and back and forth on and on. You really need atleast 2 established non-related lines to effectively line breed with and the more you know and understand about their lineage the better. Line breeding with only 1 line will become too closely related quickly and can lead to higher instances of genetic defects and sterile offspring. Line breeding is really only for experienced quality breeders, it's not something you should be doing when just starting out in breeding chins. The problems that you most often run into with line breeding is bringing out traits that are unexpected or not seen in the parents. Some times certain traits will skip a generation and then reappear in a line breeding. You have to remember line breeding will set in common traits, both good and bad traits. That is where strong evaluation needs to be done on offspring from line breeding. For example, if there is 1 bad trait like a grey belly gene in the lineage of an animal and you line breed that animal repeatedly, before you even realize it you've set that grey belly gene into that entire line and most of what you've crossed it with. This is an example of what most commonly happens when someone starts line breeding animals that they don't know the background lineage on and don't know how to evaluate the qualities and defects in their offspring from the line breeding. When done effectively by the experienced rancher of chinchillas, line breeding can be a tremendous tool to further set in good desired traits in their animals. When done by inexperienced new breeders line breeding can lead to setting in all kinds of health defects like teeth problems, fur defects like chewing, or swirly patterned lay down fur, grey bellies, grey bars, etc. Because of this serious line breeding should really only be done by experienced breeders that know and understand the lines they're working with and the backgrounds of those lines or the effects of line breeding will be more negative for your chins then positive.