At 2 years

When your baby has about 30 to 50 words in his vocabulary he will begin to put two words together.

These two words will be the words he already has in his repertoire. He may have daddy, mommy, bye-bye, car, doggie, cookie and ball.

He may combine daddy doggie which can mean Daddy is with the dog, or Daddy goes to the dog, or the dog runs to Daddy.

Consider the context in which it was said, try to interpret what he's said and tell him: Daddy doggie. Daddy is holding the doggie.

from 2 to 3 years

You will notice that he will be able to follow two-step commands. Get the book, and bring it to mommy. 

Knowing that he will be able to hold two pieces of information in his mind and perform upon them, create situations for him to practice and learn this skill. Get the cookie, and give it to the doggie.

Use new words that he may not know to help him expand his vocabulary. See the mug on the table, put it on the counter. The mug, the cup on the table, see it. He'll see the cup because he knows the word cup but he'll note that you said mug for cup.

The use of verbs will begin to increase. Use more verbs in your speech when talking to him.

Talk to him in complete but simple sentences so you can model what he will be learning at this stage. Prior to this you were using telegraphic speech... Mommy eat cookie... Sarah go night-night... Because he will be learning simple grammar in this phase, use correct grammar when talking to him, but remember to keep your sentences simple. Mommy eats a cookie... Sarah goes night-night.