Flame weeding. I will post a video on here soon to show how effectively I have used flame weeding as a post emergent herbicide. It is USDA certified systemic weed control but is not selective. From my experience it is superior to the usage of vinegar as a non selective PE herbicide.
Ask phasthound about the selective post emergent herbicides that work.
As far as effective pre-emergents, corn gluten meal is unreliable. A nice healthy green turf will out perform common weeds any day of the week.