Having a variety of plants in your garden beds will not only be beautiful, but it will attract beneficial insects that will help you with your battle against pests. Bio-diversity is key to a healthy garden. Keeping the ground covered by plants helps to maintain a more constant soil temperature and moisture level, which in turn creates a healthy environment for the plants. In order to keep your garden weed-free, you must eternally be diligent about yanking out the newcomers. It helps to follow some kind of schedule or routine, so you can ensure that the weeds never get ahead of you.
Weeds are easier to pull when the ground is wet.
You must ensure you pull out the roots, or else the weed will probably re-grow. You must not allow weeds to go to seed, or else you are defeating your efforts. In the newsletter section of this website I share the weeding schedule I follow in my own garden. I break up my garden into sections, and weed just one section each week. It's simply too overwhelming for me to tackle the entire garden at once.