Head collars of any sort only mask a problem by making it uncomfortable to pull. Not something I'd recommend for anything. Harnesses are unnecessary.
Start with a lightweight collar - a cat one would do the job. Something that's no more than half an inch wide would be good. Don't get a collar that's too heavy, it will be hard for the pup to get used to. Same goes for a lead. Pets at Home do a long, very lightweight house line which we use - it can be useful for teaching recall as soon as you get her. Our puppy collar is sized for 8 - 12 inches neck size (and I only have labs; it's done all four of them).
Don't let your pup start to pull. It is very easy. She won't have a clue what a collar is or a lead so is just never going to pull at it when you first put it on. She will be more bothered by what she's actually wearing than anything else. I expect there will be lots of sitting down and scratching at it, tbh.
Praise and treat when she walks nicely to one side of you. Don't let her stop and sniff, keep her attention 100% on you by using treats, happy singing voices, her name and which ever command you intend to use. I use 'heel'.
Do that in short bursts a few times a day and she will learn what you expect from her on the lead.
She can't guess at what you want her to do, so for everything you have to teach her. The earlier you start, the easier it will be because she won't have had time to decide for herself what it is she should do.
Don't forget. It's more important for any dog to have a perfect recall, and good heel work THAN ANYTHING ELSE. Sit and stay are handy and absolutely worth learning, but not as important for safety and ease of taking her out and about as the other two.
With those absolutely 100% perfect, you'll have a dog you can happily take anywhere. They are both easily trainable in a week or two if you have no bad habits to correct before you start!