What is a great first car for a 20 year old girl?

There are many options for you. You could try a honda civic, honda accord, toyota camry, hyundai sonata, ford focus, hyundai accent, hyundai elantra, etc. Just be sure to research the models, and decide what year car you want. Also, have the car checked out by a mechanic before you buy it. Good luck with your car search!