Most of the insects that infect garden are visual attachers. To foil them, place a canopy over your garden, if small or over susceptible plants, using shading cloth as the covering. You can find shade cloth with different degrees of light emission on the web. The shade cloth found in most garden centers is 70% so that might be to much shade for you zone.

Floating row covers, not shade cloth, is one means of control. You cover your plants with the FRC and that will help keep many insects, including beneficials, from gettng to your plants. But the single best method of insect control is to look closely at your soil and do what is necessary to make that soil into a good, healthy soil that will grow strong and healthy plants that are less desireable to insect pests.

fuzzy158, the tools available to you fall under in the category 'exclusion methods'. They include 'quarantine' - inspecting and screening new plants (fungus gnats); physical barriers - row covers, enclosed areas (fruit flies); traps - to attract and capture intruders (beetle/bug of the month); creating a hostile environment - bird and wasp friendly (caution!) ... and maybe some others that I have quite forgotten. Preventative practices like crop sanitation and closed season can also help. For optimal control, knowledge of the life cycle and feeding habits of the pest(s) are required. This will facilitate proper timing of the various activities on one's 'calender on events'.