Avoid using baby-talk. Speak to your child with normal words and phrases. Baby-talk can confuse your child and cause her to pronounce words incorrectly, inhibiting her language development.
Correct your child when she uses incorrect words or pronounces words incorrectly. Don't call attention to her mispronunciation or misuse of words, but rather restate what she has said using the proper words. For example, if she says "banilla" when she means "vanilla," say the word back to her in the proper way -- "Do you want vanilla ice cream?" She'll internalize the correct pronunciation and use of words and start using and saying them correctly.
Read to your child. Read books, signs, labels and anything else that contains written text. While reading, point out images that may represent words in the text. State words clearly. Ask your child if she knows what specific words mean, and if she doesn't, provide a definition.
Have conversations with your child. Ask questions that will illicit responses. Encourage her to share her ideas. Engaging in a dialogue will prompt your child to speak, hear and use language in a meaningful way.
Use new and descriptive words when talking to your child. Instead of asking her if she wants to play with the ball, ask her if she wants to play with the (insert color) ball. The more your child hears new and descriptive words, the more likely she will use them herself.