1) space plants widely. This allows their roots to reach maximum potential, so that the plants become more drought tolerant, stronger, and more productive. Wider spacing also means fewer diseases and slower transmission between plants when diseases do occur.
2) direct seed, rather than prestarting inside, when at all possible. Seedlings started outside are stronger and more adapted to their final environment. When seeds are grown inside, the environment is so benign, that even weak and disease prone seeds will grow. Then, when they are planted outside, they fall victim to any number of troubles. Moreover, seedlings grown in a windless environment never develop strong stems. Wind actually exercises plant tissues.
3) some crops, like tomatoes and peppers, require early starting in seed pots, in order to fully develop in one North American season. In those cases, start seeds in a mixture of your own gardening soil plus a something to lighten it, like peat. By starting in ordinary garden soil, rather than a sterilized potting soil from a garden center, your seeds will develop in an environment more like your own garden. Plant several seeds per pot and expect some to fail. At this stage, failure is good. It means that the weaker seeds, those that would have been subject to disease in your garden, will not get planted out. You won't waste your time trying to grow less vigorous stock. Production will increase.
More on this great book later.