With your garden, instead of planting one row of the same plant, mix it up. For example, plant your onions next to your broccoli. You can even add an ornamental plant to the row. The visual contrast, as well as the different scents can confuse and deter certain pests.
Another technique is planting marigolds. They can actually lessen the damage caused by pests like grubs.
At the end of every season, make sure to clear your garden of any debris, such as dead leaves and plants. By doing this, you are preventing any insect larvae from overwintering in your garden.
Of course, you can also visit your local Farmers Co-op and check on the assortment of pesticides, fertilizers and mulches to help you keep your garden health, happy and bountiful.