3. Consider The Readiness Method
The "they will go when the time is right" approach, popularized by Dr. T. Berry Brazelton, is both the most common method in the United States as well as the one adopted by the American Academy of Pediatrics. 

In this child-directed method, you introduce the potty and all related tasks, but you wait for your child to exhibit signs of readiness (interest in staying dry and clean and in the potty itself) and essentially allow them to train themselves. The downside is it takes a long time and can result in being trained at a later age.