You don't have to spend a lot of money to teach your baby. What I do/did:
1. Since he was born, I talked a lot to him (everytime when he was awake). I told him what I was doing at the time (opened the curtain, changed his clothes, etc). You just need to drink a lot of water after all that talking!
Before he was 1 month, he could respond back when I talked to him. 6 months, he could say: mama and papa. When I talked about the window, he turned his face to the window (I didn't even have to point it to him) etc.
2. I read books with him everyday. From here he got to know a lot of vocabularies. You don't have to buy expensive books, too.
3. When I brought him outside, I told him all the things we saw.
3. When he was 7 months old, I started to sign to him (any book will do). He signed back when he was 9 months old. We continued to use sign language till he was 12 months (by this time he could sign 50 signs already).
At 1 year, he started to talk. At 16 months, he already talked in long sentences.
His vocabulary at 2 years: more than 1000 words in English, and a few hundred words in Chinese. He could sing, and recite poems in English and Chinese. He knew colors and shapes, and could count things till 15.
Now, I try to introduce at least 1 new word everyday.
So, the key is : you (and your mouth, of course). Just talk to him everyday, tell him the names of the things around him, sing&read to him.
