At the Blue Cross we use Drontal and administer one tablet for every 10 Kg of body weight. Puppy Drontal (which is a liquid) is adminstered again by weight, but needs to be done every two weeks until the pups are 12 weeks old but only covers roundworm.
Please don't buy Supermarket pills/sprays for worming or de-flea'ing as they just don't work - depending where you live (ie do you walk in places where there are cattle or sheep?) then ticks can also be a problem .... Don't try and get them off yourself unless you are confident, as the mouthparts can stay embedded and cause an infection .... On a short-haired dog you can maybe smother them with petroleum jelly, but on multiple infestations, Zap them with Frontline !!
Dogs don't seem so often affected, but at the Blue Cross we have had kittens brought in which have been sooooo covered with lice and ticks that they are actually sucking the life out of them ..... On their little tiny bodies, these parasites are really life-threatening !!