Vocabulary will play a big part in your child's toilet learning. Before you begin, decide what words to use. You and your parenting partner will both need to be comfortable with this language; use words that are accurate but easy for your child to understand.
You'll also need to purchase a potty chair and training pants and/or underwear. You may wish to bring your child along to pick out her own potty chair and trainers. Make the day special and discuss with your child the significance of learning how to use the potty.
Before your child sits on the new potty, talk about what he/she can expect. Point out that Mommy and Daddy use the potty. Then try a couple "test runs" in the bathroom. Without taking off her clothes or diaper, show your child how to sit on the potty (most pediatricians recommend starting boys out sitting, too). Your child's feet should be firmly planted on the floor or a step-stool. Also, demonstrate how to wipe (girls should always wipe from front to back to avoid bladder infections) and talk about flushing and where the contents of the toilet go. Be sure to enforce healthy hygiene: you and your child should always wash your hands when leaving the bathroom—even if you are just "touring" the facilities.
Many children also benefit from the many toilet-learning products available. There are self-wetting dolls for boys and girls (complete with their own potties), training books, and various DVDs and videos.