She is old enough to not have many accidents, but may have one now and then until she is accustomed to wearing only panties. This means, of course, that if you do away completely with the diapers or pull-ups, she is going to have an accident here and there which may be frustrating to you, but remember it is also frustrating to her and very uncomfortable to have wet panties on. This is, however, what will help to motivate her to NOT wet her panties. You must be extra diligent in asking her if she needs to go potty. Girls generally potty train much earlier than boys and with due diligence and attention, she should be completely potty trained in a short period of time. When you are out and about, be prepared to visit every bathroom in every store you enter; that is normal for a three year old, and it also will teach her that potty is always available. Just ask her very often when you're outside the home and take her to the bathroom frequently to try and eventually she will get the idea. Definitely do away with the pull-ups/diapers, though. It only encourages her to be lazy about going potty at this age.