Ground beetles require the cover provided by low-growing plants. Lacewings lay their eggs in shady, protected areas, so providing such places near crop plants is a good idea. Selective weeding can encourage beneficial insects by leaving potential food sources in the garden. Allowing certain volunteers to remain in the garden is somewhat like random companion planting. Just know what weeds or volunteers are helpful.
Tiny flowers produced in large quantity are much more valuable than a single, large bloom.
Fennel, angelica, coriander, dill, and wild carrot all provide in great number the tiny flowers required by parasitoid wasps. Various clovers, yarrow, and rue also attract parasitoid and predatory insects. Low-growing plants, such as thyme, rosemary, or mint, provide shelter for ground beetles and other beneficial insects. The wasps will catch caterpillars and grubs to feed their young, while the predatory and parasitoid flies attack many kinds of insects, including leafhoppers and caterpillars. Of course, you also may plant species that are not noted for harboring beneficial insects.