* Decide what whelping facilities, including bedding, are most appropriate.
whelping boxes are a first choice, and can be found online , or used on forums ( when buying used, be sure items are not infected with Parvo, this could be deadly to your litter) .   Whelping boxes have high sides and pigrails to ensure Dam will not lay on a puppy and suffocate it to death.  They also usually have a door for Dam to get out for potty breaks.
Lighting is optional, and can provide heating for puppies when needed. Heating pads are also an option.
Placing your Dam in her whelping area a week or two prior will ensure she is
comfortable with the area and not too stressed to go into labor.

         Bedding -  Dam will require bedding prior to whelping , she will use this to nest prior to giving birth.
Choose towels you will have no problem throwing away, you will want to discard these after delivery.
You can use disposable pads, using the type you buy at Walgreens,  ( these are commonly used as bedding pads for the elderly),
they look just like puppy pads with put the scent and come in larger sizes.  Make sure you place these right before delivery, or your Dam may shred them. 
Tape them to the bottom of your whelping box, these are good
 because you can toss, and they are white, you really want to be able to see what color your Dam's fluids are. 

         Dam Changes- As she gets closer to to giving birth you will see a change in the Dam. 
She will pace, she may have diarrhea the same day or the night before. 
Your Dam usually stops eating all together with 24hrs. of giving birth.
Checking her anal temperature will give you a good indication of when to expect puppies, 
her temperature will drop from around  101 to 98 and remain there when she is ready to go into labor.
Many breeders free whelp, we want dogs capable of this, however it is always important
you be present for your Dam, in case she needs assistance,
puppies can get stuck and need assistance ( unless you are knowledgeable do not attempt to assist, this is where you want your Vet on call, he can assist you and direct you on how to best help your Dam) . Your Dam may make no progress after labor begins and need a emergency cesarean.
When labor progresses your Dam should begin to pace , some pant, some do not, at some point they begin to push.
When they push more than 45 min on one puppy and nothing occurs , call your vet.
When they push and a sac appears, and your Dam ruptures the sac , call your vet.
If more than one sac appears and both are ruptured , call your vet.
Get the jest here.
You want to see puppies , not just sacs.
If you see green in your ruptured sacs, call your vet.
Be sure your vet will be available 24hrs. , your Dam is your 1st priority.

*  Puppies should be born between 30 min - 1  hr apart, depending on your Dam, do not panic. If too much time has elapsed and she has pushed with no progress, Call your vet.
     You will see a significant change in her belly size when she is done, it will still feel , like she may have a puppy, she is however done.  All of her teats should be soft , not hard. Check each puppy, make sure they are nursing well. Check your puppies every 20-30 minutes to be sure they are doing well and warm. Take your Dam out to potty, and try to feed her. You can now start her on calcium tablets.

      Congratulations you have whelped a litter.

   * Ensure that you have the necessary equipment to deal with the whelping

what do you need on hand...

Have more than one, in case you vet in un available,
keep the number for your local Emergency Vet , just in case