I do not believe in worming every month -- none of my dogs manifest any signs of worms and worming medicine is a poison that I think should be administered for cause, or at least with less vigor than some dog owners believe.
That said, worming has never been easier. Roundworms and tapeworms are the most common canine worm types and highly effective over-the-couner worming medicines for these worms have been available for decades. For simple regular worming, go with these.
If you think a dog has hook or whip worms, as well as round worms and tapeworms, try Safe-Guard (10% Fenbendazole). This medicine is now available in dog-ready packages from most online veterinary supply places, but if you have a very large kennel a less expensive version can be made up from SafeGuard used for horses, provided the following dosage directions are carefully followed. The dosage for canines is 1 ml (which contains 100 mg active ingredient) per 5 lbs of dog bodyweight. For example, a 15 lb terrier would receive 3 ml (same as 3 cc or about two-thirds of a teaspoon) per day for a 3 day period.
Fenbendazole is always administered for 3-consecutive days rather than only one day, to be sure the puppies and dogs are 100% worm-free.