The most important thing to do when talking to your baby is bombarding them with lots of language. Talk about everything! Do it in a way that is animated and interesting. You’re going to look goofy, if you don’t, you’re doing it wrong ;). Do your best to use short sentences or two-word phrases (e.g., milk want?) to help your baby process what is being communicated.
In conjunction with a short phrase, you should also employ representational gestures (AKA sign language). Be intentional and thoughtful about the short phrases you can use throughout the day. Take some time to think about some short phrases you can use… Lastly, when your baby is beginning to make raspberry sounds or cooing, remember to imitate them. Imitating your baby will eventually lead to him or her imitating you!