Ditch the Pull-ups: They Hinder Instead of Helping...
While it may seem tempting to use pull-ups, at least with younger children, they tend to hinder the process of potty-training.
We started potty-training my daughter around the age of 19 or 20 months. She showed all the signs of readiness, which is all it takes, aside from parental dedication. (Don't expect them to already know how to do it!) It may have helped that a) she was a girl, and b) we had used cloth diapers lots of the time, so theoretically she knew what it felt like to be wet. But my pediatrician told me before we started the process not to buy into the whole pull-up hype.
In order to learn what it feels like to need to use the potty, and what it feels like to have an accident, a child must be able to feel it when they pee, and also must know that they need to speed to the toilet as soon as the urge strikes. When we first started, we would try to have my daughter still wear diapers when it wasn't "convenient" for her to have an accident-Sunday school, people's houses, etc. We had great success with her at home when she wasn't wearing any underwear (after a few days of accidents, of course), but whenever we put those undies on, she'd just pee away in them! She couldn't tell the difference between when she was wearing panties and when she was wearing diapers until it was too late. She didn't like having accidents in the panties, but when she was playing and thinking about other things, she wasn't thinking about what was on the bottom.
In short, we just bit the bullet and had her go straight to underwear. Now she is used to them, and knows that if she's not in bed, and she needs to potty, she needs to head for her potty chair or the toilet. If your child is willing to try on demand, it may work differently, but Selah is very strong-willed, and doesn't want to be told when to use the potty. Thus it is important that she knows when she needs to go, and that the same undesired result will happen every time if she doesn't-a wet bottom and wet legs!