I like to start with a harness for young puppies, I find that my puppies have been prone to backing out of collars so just feel more secure with a harness until they are confident in their surroundings. Then I switch to a martingale for walking, and use a harness for hiking and nosework. I generally don't use the front attachment / no pull harnesses, as I look for things don't constrict movement.
I agree! I used a harness initially with my pup on the advice of my trainer. A harness allows a puppy freedom to move about to pull to investigate, sniff, happily greet people etc. without becoming at all accustomed to the feel of pulling against a collar and without inadvertently getting "corrected" during what should be positive socialization .
In the meantime, take some treats on your walks and when your pup is next to you, pop a treat in her mouth, this teaches that walking next to you is really great!Then you can introduce the collar slowly to teach a nice loose leash walk.
I can't tell you how wonderfully this worked for my pup. She's now almost 10 months old and I've virtually never had her pull a leash on a collar. I can walk her down my ice/snow covered driveway and know she's not going to make me slip, she walks nicely around other dogs, kids, people, whatever and I've never used more than a martingale or flat buckle collar. That's probably way more info than what you were looking for, but it worked really well for us!