I don't know how many times I've heard parents proudly proclaim that they never talk baby talk to their baby! There's a very strong misconception amongst parents that baby talk is not a proper way to talk to a baby. How else should we talk to our babies???
I'm not saying I'm constantly gagagoo-ing at babies. I don't consider this baby talk because it's actually not 'talk' at all. But when I'm interacting with babies I'm very expressive (wide eyes, big mouth, lots of smiles), I change the pitch of my voice and I slow down what I say. What comes out of my mouth still has meaning, but the way I say it makes me more interesting to a baby, so that the baby will pay more attention. This is such a natural way to communicate with babies that mother's in nearly every culture do it quite naturally.
Many parents seem to be afraid of "dumbing" their communication down too much for their babies, but babies need these extra cues from adults. It actually helps them learn language, instead of holding them back.
When you talk to a baby, treat him like a baby, rather than a little adult. Be sure to use correct grammar and complete sentences, but try and say less words than you would say to another adult.