The simplest way of controlling weeds is too hand pull them. However, in some cases weeds can be too widespread too effectively hand weed. Then I guess it depends if your trying to control grass or broadleaf weeds.
If the couch goes dormant (totally browns out over winter) then you can simply apply glyphosate and it will kill all the weeds no matter if grass or broadleaf. Adding a spray buffer or an appropriate spray adjuvant will guarantee the best possible results.
If your wanting to control weeds in couch when it’s growing then use a broadleaf post emergent herbicide is the way to go. If you want to stop them from becoming a problem use a pre emergent herbicide.