This requires knowledge of pest life cycles. Many pests over-winter in the crop debris of host plants or in the soil around host plants. Tilling can disrupt pest habitats. Be careful not to damage plants. Pests can be squashed or dropped into a jar of soapy water.
Many native plants are good choices.
A floating row cover is an excellent material for excluding insect pests. Other examples are paper collars for cut-worms and diatomaceous earth for slugs. Rotate crops that are prone to pests and diseases. However, it is often very difficult to rotate away from disease problems in small gardens that over-winter in soil or garden debris.