1. Read aloud to your child
Do you have a library card? Is there a used bookstore near your home? Get five to seven books and read one aloud each night of the week. Stick with a theme or get a few very different books. This step leads directly into the next one which will be to ... Read the books until your child is finishing your sentences or "reading" them to you from memory. At that point, go get more books!
2. Build vocabulary
When choosing books, try to pick a couple that have unfamiliar topics to your child's daily activities. For example, if you live near the beach, pick a book that depicts a snowy mountain as it's scenery. If you live in a busy city, choose a book about a farm.
Another way to work on building vocabulary--Point out the things that are unfamiliar as you are driving in a car or going for a walk. When in a new store, take a few minutes to walk around and look at things that you may not have at home. Talk about what they are used for by using overly descriptive language.
3. Ask questions
When reading a book, riding in the car, going for a walk, taking a bath, getting dressed... Get the point? Ask Questions! Try to ask four to five questions with each page of the book, with each new place you go, at the store, or at the playground.
Stick to these words to start your questions: Who, What, When, Where, Why.
Incorporating these three things into your every day routines will have a lasting impact on your child's language development and expressive abilities.