For broadleaf weeds, you may want to try watering in some non-sulfured molasses. When it comes to these type of weeds, molasses is great because most broadleaf weeds need high nitrate levels. When you add molasses, you get bacteria, and some fungi growing, but mostly bacteria. These organisms take up nitrate and turn it into biomass, so the weeds will be less able to compete with the desired plant.
When you have sour grasses, like quack grass, crab grass, foxtail, nutgrass, goosegrass, johnsongrass and barnyard grass, those are a lack of a signal, a lack of the calcium signal. This is natures way of trying to regroup calcium and bring it to the topsoil. Try applying bonemeal to your soil to control these or I've found a fish hydrolysate by Schafer Organic Fish that contains 12% Ca. That's the most I've ever found with any fish product.
Now if you have heathly turf, weeds won't be able to compete for space. But this just doesn't happen, you have to work at it. Weeds are indicators of what's missing in your soil, and actually work to draw what is missing from deep in the soil. So you need to pay attention to what weeds you have and what they are telling you.