There's more approaches to breeding than breeders for sure. Each breeder has differing goals, priorities, tastes, resources, knowledge base, and market venue. There's waaaaay to many ways to answer that one.
Edit: From a genetic perspective?
A breeder doesn't always select with the same goals in mind with each mating. The intended purpose of the breeding might be to lock-in desired traits or characteristics with a linebreeding, as opposed to an outcross for hybrid vigor. Opposite swings of the same pendulum, the goal direction depending on the current state of the selectable breeding stock.
Breeding like-to-like, by phenotype, was perhaps the 'only way' before the works of Mendel and field of modern molecular genetics, where genotype could be considered. Some breeders don't hardly consider the actual dogs they select (cough, cough) and simply try to place the most/best names on the produced litter's pedigree (the Melting-pot method?).
Reproductive isolation of bloodlines create distinct "gene pools," almost separate breeds. The west-working, "DDR", and czech gsd lines are nearly such, and crossing them (with careful consideration) produces higher levels of heterosis (hybrid vigor) than would crossing a pair from a genetically common population (because of prolific sires). Dogs of higher levels of heterosis are often the better "performers", while linebred ones are better producers because of homogenous locked-in traits that empower the breeder with better control of what is being produced.
Or, are you simply looking for good reading referals? There's not a 'single' how-to approach; you just have to incorporate everything you know into all that you have available to you to produce the best you can. Learn from that, and how you can do even better the next time. Essential ingredients: inquisitive nature, strong imagination, bold decision making, good manners, thick skin.... and maybe some sleeping pills.