To get dog hair off your couch first take your hands and pull off as much of the dog hair as you can with your hand and then use a lint roller on the couch to lift up the leftover dog hair.
You may have to go over the couch a few times to get all the dog hair off the couch with the lint roller.
You can also buy a pet hair magnet that works great for getting pet hair off of couches and other upholstery.
After using the lint roller or pet hair magnet to remove as much dog hair as you can then go over the couch again with a vacuum cleaner.