1) have your dogs protected against kennel cough. This is a very simple procedure at the vet's. The vaccine is administered by inhalation: the vet puts drops of the vaccine in the dog's nose or sprays it up the nostrils. As with all protection, make sure it is done with enough time in hand for it to be fully effective.
2) make sure that the kennel is one that insists on proof of vaccination against kennel cough. Some don't.That's a good sign of the level of care that you may expect. It's not much of an answer to say that the disease is not life-threatening or that that kennel has never had a case, as one told me once

: Once it arrives it spreads very quickly though a kennel and can leave a lot of distressed dogs (and unhappy owners).
3)A) All kennels should also demand proof of protection against the other significant diseases, such as parvovirus, that your vet should have protected your dogs against.
3)B)Obviously you should have the protection up to date. If any is needed it is very important that it be provided in full and in good time, so that the protection has taken full effect before the dog goes into kennel.
4) Ask to see the facilities. First impressions count for a lot.You can tell very quickly whether the inmates seem happy and the place seems very clean .
5) A good kennel will always ask what food the dog is used to. Whilst dogs eat almost anything
eventually it remains true that they are not keen on a sudden or radical chance of food on arrival. It is usually just a question of the dog only eating dry food at home or only having tinned meatloaf or morsels there, as its main food.Suddenly give it the other stuff and it'll refuse to eat for a while.So it needs to be introduced gradually, if at all, to the other stuff.The ideal kennel will only give it the type of food it is used to and not try to change its habits.