For an older dog, fleas are easy to get rid of. However, flea control for puppies must be done differently if they are under 8 weeks of age.
The topical preventatives for fleas that are on the market today, are safe to use on puppies that are at least 8 weeks of age, but can not be used on pups that are younger than that.
I've never had a puppy with fleas, as I always make sure that the mommas are treated before giving birth.
If you obtained a puppy that has fleas, and is under 8 weeks of age, then getting rid of fleas will be a situation of doing the best you can until the puppy grows older.
Never use flea shampoo on a puppy under 12 twelve weeks of age. It is dangerous to use on them, even if the shampoo claims to be safe on puppies.
These types of shampoos are ineffective and not even necessary if you are using a topical flea treatment ointment.
For a young puppy, flea treatment will have to consist of using a flea comb, lots of vacuuming, and daily washing of her bedding until she is old enough to be treated safely.
Flea collars are ineffective, and using them a on young pup also poses a dangerous risk to her health.
Do the best you can with combing her daily, vacuuming, and washing her bedding until she reaches 8 weeks old, then put her immediately on a topical preventative.