And, as an addendum to the weeding tip above, I just read an article recently on weeding, and a number one tip was to remove the root of the weed with as little disturbance to the surrounding soil as possible. Which is why a knife would be perfect -- a serrated knife is even better, as you can sink it down under and cut the root below ground.
According to the article, there are weed seeds ALL OVER THE GROUND, approximately 3"-4" below the soil. The weeds need LIGHT to germinate. Without it, they just stay in a dormant state underground. Pulling a weed up and disturbing the ground exposes the pre-existing seeds to light! We can, in fact, cause even more weeds to grow, by the way we perform our weeding!
Be advised!