I would say for newbie females or not, I would say a .22 like a Buck Mark or Ruger. Cheap to purchase and cheap to shoot. Small and light for easy grip and control. Especially for newbies a gun is very intimidating so starting them off on something small gets them more comfortable and familiar with the basics of safety and operation before upgrading them to something bigger. These are also easier to manipulate, load, and clear thus making it easier for the "instructor" to foster safe and good habits. And since its less intimidating its often more fun.
I have small short asian girly hands and prefer single stacks because I am able to have a more secure hold on the weapon when firing (esp if its a larger caliber). I have a Ruger Mark III that I start everyone out on. I also have a Sig Sauer Mosquito (.22) that looks more intimidating but functions a lot like my ruger. This is often gun #2 when I am introducing someone new to semi-autos. Then I have my baby the Springfield EMP (9mm). This is fits my hand like a glove! When my friends feel comfortable and I feel they are safe enough I often move them to this. TI also have a glock 26 but that is a double stack and has a bit of a thicker grip. Its upside is that its light and small. This is gun #4 in the line up. I hope this helps but I have fond my 22s to be irreplaceable when teaching. I have even had my 8 year old cousins shooting on them. The caliber I expose to new shooters is really determined by them and how they handle/deal with the smaller calibers. I have had friends that are completely unphased by the 1911 and I have had others that scream and nearly drop the Ruger after the first shot.
If you need someone to help test out guns im always available to go shooting