Join the Republicans and get President Trump to build a wall .
Seriously some weed seeds can persist in the soil for better than 40 years so any one who thinks they are going to have a perfect lawn without lots of work is deluding themselves .
As there are around 250,000 different common grassland weeds , without some means of identifng your intruders you are not going to get much of a useful answer
Some weed pull
Others will break off the roots in 20 places and then generate 20 new weed plants
Some you fertalize to kill ( mostly broadleaves ) some you starve, some you burn , some you use glyco on, others require a pre-emergent poison at a specific time of the year and either just before or just after rain.