First take some rubber gloves and get the rubber gloves damp and then use the damp rubber gloves to pull away as much dog hair as you can from the clothing.
Then use a lint roller to run over the clothing and remove as much of the dog hair from the clothes as you can.
After that throw the clothes into the washing machine and add a cup or two of vinegar to the wash cycle as the vinegar will help to loosen the dog hair from the clothes that is left over.